https://calculum.dev/blog/ Practical notes on the questions people bring to Calculum calculators. en-us https://calculum.dev/blog/what-margin-does-wholesale-leave-compared-with-retail/ https://calculum.dev/blog/what-margin-does-wholesale-leave-compared-with-retail/ Sat, 14 Nov 2026 00:00:00 GMT Calculate wholesale and retail gross margins, profit per unit, and a blended margin using a $12 product sold at $18 wholesale and $32 retail. https://calculum.dev/blog/what-roas-do-i-need-to-break-even/ https://calculum.dev/blog/what-roas-do-i-need-to-break-even/ Fri, 13 Nov 2026 00:00:00 GMT Calculate break-even ROAS from contribution margin, compare 2x and 3x returns, and see what an $80 sale leaves after product costs and advertising. https://calculum.dev/blog/how-much-revenue-is-sitting-in-abandoned-carts/ https://calculum.dev/blog/how-much-revenue-is-sitting-in-abandoned-carts/ Thu, 12 Nov 2026 00:00:00 GMT Calculate cart abandonment rate and model recoverable revenue with a $51,000 example. See why unfinished cart value differs from sales and profit. https://calculum.dev/blog/how-do-i-calculate-repeat-purchase-rate/ https://calculum.dev/blog/how-do-i-calculate-repeat-purchase-rate/ Wed, 11 Nov 2026 00:00:00 GMT Divide repeat buyers by unique customers, then multiply by 100. See a 30% worked example, compare revenue share, and avoid mixing reporting periods. https://calculum.dev/blog/how-do-i-calculate-sales-quota-attainment/ https://calculum.dev/blog/how-do-i-calculate-sales-quota-attainment/ Tue, 10 Nov 2026 00:00:00 GMT Divide closed revenue by your quota, then multiply by 100. Work through a 75% example, the bonus threshold, and why team attainment needs weighted totals. https://calculum.dev/blog/does-a-raise-keep-up-with-the-cost-of-living/ https://calculum.dev/blog/does-a-raise-keep-up-with-the-cost-of-living/ Sun, 08 Nov 2026 00:00:00 GMT A 4% raise on a $72,000 salary, set against a 3.2% cost-of-living change, leaves $576 a year. That is $22.15 on each of 26 paychecks. The percent comes from the CPI series you choose. https://calculum.dev/blog/does-a-contractor-or-an-employee-cost-less/ https://calculum.dev/blog/does-a-contractor-or-an-employee-cost-less/ Sat, 07 Nov 2026 00:00:00 GMT An employee costs salary times one plus the burden percent, plus overhead. A contractor costs the rate times the hours. The defaults are $129,000 and $128,000. https://calculum.dev/blog/does-a-monthly-retainer-beat-a-project-pipeline/ https://calculum.dev/blog/does-a-monthly-retainer-beat-a-project-pipeline/ Fri, 06 Nov 2026 00:00:00 GMT A retainer is the monthly fee times the months you bill. Project fees are one job times how many you invoice. At the defaults, $4,000 a month beats five $8,000 projects by $8,000. https://calculum.dev/blog/how-do-i-calculate-accounts-receivable-turnover/ https://calculum.dev/blog/how-do-i-calculate-accounts-receivable-turnover/ Fri, 06 Nov 2026 00:00:00 GMT Receivables turnover is credit sales divided by average receivables. $365,000 on a $30,000 average turns 12.17×, or 30 days. Examples cover slow payers, cash sales, and a blank opening balance. https://calculum.dev/blog/how-do-i-calculate-average-order-value/ https://calculum.dev/blog/how-do-i-calculate-average-order-value/ Fri, 06 Nov 2026 00:00:00 GMT Average order value is period revenue divided by completed orders. $48,000 across 400 orders is a $120 ticket, with 3 items at $40 each. Ten examples cover refunds, wholesale, and shipping. https://calculum.dev/blog/how-do-i-calculate-debt-service-coverage-ratio/ https://calculum.dev/blog/how-do-i-calculate-debt-service-coverage-ratio/ Fri, 06 Nov 2026 00:00:00 GMT Debt service coverage is net operating income divided by the year's loan payments. HUD reads a ratio under 1.0 as a shortfall. Defaults of $72,000 of income on $42,000 of payments come out at 1.71×. https://calculum.dev/blog/how-do-i-calculate-net-promoter-score/ https://calculum.dev/blog/how-do-i-calculate-net-promoter-score/ Fri, 06 Nov 2026 00:00:00 GMT Net promoter score subtracts the detractor share from the promoter share. Sixty promoters and fifteen detractors in 100 answers score 45, and passives stay in the count. https://calculum.dev/blog/how-many-visitors-does-an-ab-test-need/ https://calculum.dev/blog/how-many-visitors-does-an-ab-test-need/ Fri, 06 Nov 2026 00:00:00 GMT Each variant needs the squared sum of the significance z and the power z, times both conversion variances, divided by the gap squared. From 20% to 30% that is 291 visitors per variant. https://calculum.dev/blog/should-i-take-an-owner-draw-or-a-salary/ https://calculum.dev/blog/should-i-take-an-owner-draw-or-a-salary/ Fri, 06 Nov 2026 00:00:00 GMT A draw is taxed on 92.35% of the amount at 15.3%. A salary splits that 15.3% into 7.65% employee FICA and 7.65% employer FICA. On $80,000 the draw keeps $68,696.36 after self-employment tax. https://calculum.dev/blog/what-hourly-rate-does-a-freelancer-keep-after-tax/ https://calculum.dev/blog/what-hourly-rate-does-a-freelancer-keep-after-tax/ Fri, 06 Nov 2026 00:00:00 GMT The rate you keep is billed revenue minus expenses, after a tax reserve, divided by every hour you worked. At $150 an hour the default month keeps $65 of that. https://calculum.dev/blog/what-is-a-good-quick-ratio/ https://calculum.dev/blog/what-is-a-good-quick-ratio/ Fri, 06 Nov 2026 00:00:00 GMT The quick ratio divides cash, receivables, and other current assets except inventory by debts due this year. The defaults come out at 1.5×. A stock-heavy shop on the same test can sit at 0.38×. https://calculum.dev/blog/what-is-the-saas-rule-of-40/ https://calculum.dev/blog/what-is-the-saas-rule-of-40/ Fri, 06 Nov 2026 00:00:00 GMT The Rule of 40 adds revenue growth to a profit margin. Bessemer treats 40% or more as the published screen. Growth of 25% and a margin of 18% score 43%, which is 3 points above that line. https://calculum.dev/blog/how-do-i-calculate-a-project-payback-period/ https://calculum.dev/blog/how-do-i-calculate-a-project-payback-period/ Thu, 05 Nov 2026 00:00:00 GMT Simple payback is the outlay divided by annual net cash. A $40,000 machine that leaves $16,000 a year pays back in 2.5 years, which is 30 months. https://calculum.dev/blog/how-do-i-calculate-conversion-funnel-revenue/ https://calculum.dev/blog/how-do-i-calculate-conversion-funnel-revenue/ Thu, 05 Nov 2026 00:00:00 GMT Ten thousand visitors at a 2.5% conversion and an $80 order produce $20,000. Ad spend of $2,000 is $8 an order and 10 times return on ad spend. https://calculum.dev/blog/how-do-i-calculate-days-payable-outstanding/ https://calculum.dev/blog/how-do-i-calculate-days-payable-outstanding/ Thu, 05 Nov 2026 00:00:00 GMT Days payable outstanding is accounts payable divided by credit purchases, times the days in the period. $30,000 on $365,000 of purchases is 30 days. https://calculum.dev/blog/how-do-i-calculate-operating-profit-margin/ https://calculum.dev/blog/how-do-i-calculate-operating-profit-margin/ Thu, 05 Nov 2026 00:00:00 GMT Operating profit is revenue minus cost of goods sold minus overhead. The FDIC studio example, $100,000 of sales, comes out at a 50% operating margin. https://calculum.dev/blog/how-do-i-calculate-project-internal-rate-of-return/ https://calculum.dev/blog/how-do-i-calculate-project-internal-rate-of-return/ Thu, 05 Nov 2026 00:00:00 GMT Internal rate of return is the discount rate that sets net present value to zero. On a $50,000 outlay and $15,000 a year for five years, that rate is 15.2%. https://calculum.dev/blog/how-do-i-calculate-project-net-present-value/ https://calculum.dev/blog/how-do-i-calculate-project-net-present-value/ Thu, 05 Nov 2026 00:00:00 GMT Net present value discounts each year's cash, then subtracts the outlay. $15,000 a year for five years at 8% is worth $59,890.65 today, so a $50,000 project has an NPV of $9,890.65. https://calculum.dev/blog/how-do-i-calculate-return-on-investment/ https://calculum.dev/blog/how-do-i-calculate-return-on-investment/ Thu, 05 Nov 2026 00:00:00 GMT Return on investment is the gain divided by the amount invested. $25,000 that comes back as $32,500 is a 30% holding-period return, and 9.1% a year over three years. https://calculum.dev/blog/how-do-i-calculate-revenue-per-employee/ https://calculum.dev/blog/how-do-i-calculate-revenue-per-employee/ Thu, 05 Nov 2026 00:00:00 GMT Revenue per employee is annual revenue divided by headcount. A $1,200,000 year with eight people is $150,000 each, and payroll takes 40%. https://calculum.dev/blog/how-much-more-do-i-need-to-sell-to-offer-a-discount/ https://calculum.dev/blog/how-much-more-do-i-need-to-sell-to-offer-a-discount/ Thu, 05 Nov 2026 00:00:00 GMT A discount comes out of contribution per unit. A 10% cut on an $80 price with $48 of variable cost needs 33.3% more units, 166.7 extra on a base of 500. https://calculum.dev/blog/what-happens-to-profit-if-i-raise-my-price/ https://calculum.dev/blog/what-happens-to-profit-if-i-raise-my-price/ Thu, 05 Nov 2026 00:00:00 GMT A 10% price rise on an $80 unit, with sales down 8%, adds $4,800 of contribution. The volume drop that holds contribution flat is 20%. https://calculum.dev/blog/how-do-i-calculate-customer-churn-rate/ https://calculum.dev/blog/how-do-i-calculate-customer-churn-rate/ Wed, 04 Nov 2026 00:00:00 GMT Customer churn divides customers lost by the opening count. Revenue churn divides lost MRR by starting MRR. Ten worked examples show when the two rates split. https://calculum.dev/blog/how-do-i-calculate-gross-profit-margin/ https://calculum.dev/blog/how-do-i-calculate-gross-profit-margin/ Wed, 04 Nov 2026 00:00:00 GMT Gross profit margin is gross profit divided by revenue. IRS Publication 334's shop, with $300,000 of net receipts and $200,000 of COGS, comes out at 33.3%. https://calculum.dev/blog/how-do-i-calculate-inventory-turnover/ https://calculum.dev/blog/how-do-i-calculate-inventory-turnover/ Wed, 04 Nov 2026 00:00:00 GMT Inventory turnover is cost of goods sold divided by average inventory. Days on hand flips that ratio. Ten examples cover a year, a quarter, and two common mistakes. https://calculum.dev/blog/how-do-i-calculate-mrr-and-arr/ https://calculum.dev/blog/how-do-i-calculate-mrr-and-arr/ Wed, 04 Nov 2026 00:00:00 GMT Ending MRR adds new and expansion revenue and subtracts churn. Start at $20,000, add $3,000 of net new MRR, and the month ends at $23,000. ARR is $276,000. https://calculum.dev/blog/how-do-i-calculate-net-profit-margin/ https://calculum.dev/blog/how-do-i-calculate-net-profit-margin/ Wed, 04 Nov 2026 00:00:00 GMT Net profit margin is net profit divided by revenue. The FDIC studio example, $100,000 of sales after costs and a $10,000 tax estimate, comes out at 40%. https://calculum.dev/blog/how-do-i-calculate-the-future-value-of-an-annuity/ https://calculum.dev/blog/how-do-i-calculate-the-future-value-of-an-annuity/ Wed, 04 Nov 2026 00:00:00 GMT The future value of an annuity compounds equal deposits. A $500 monthly deposit at 5% for 10 years ends at $77,641.14, with $17,641.14 of interest. https://calculum.dev/blog/how-do-i-calculate-working-capital-and-the-current-ratio/ https://calculum.dev/blog/how-do-i-calculate-working-capital-and-the-current-ratio/ Wed, 04 Nov 2026 00:00:00 GMT Working capital is current assets minus current liabilities. The current ratio divides those totals. The quick ratio removes inventory. Nine snapshots show when the three numbers disagree. https://calculum.dev/blog/how-is-the-cash-conversion-cycle-calculated/ https://calculum.dev/blog/how-is-the-cash-conversion-cycle-calculated/ Wed, 04 Nov 2026 00:00:00 GMT The cash conversion cycle adds inventory days and receivable days, then subtracts payable days. Ten examples run from a 91.3-day default to a negative cycle. https://calculum.dev/blog/what-is-a-good-days-sales-outstanding/ https://calculum.dev/blog/what-is-a-good-days-sales-outstanding/ Wed, 04 Nov 2026 00:00:00 GMT Days sales outstanding is receivables divided by credit sales, times the days in the period. The SBA calls this Days Receivable. Examples compare terms and cash sales mixed in. https://calculum.dev/blog/what-is-contribution-margin/ https://calculum.dev/blog/what-is-contribution-margin/ Wed, 04 Nov 2026 00:00:00 GMT Contribution margin is price minus variable cost. On a $50 price with $30 of variable cost, the ratio is 40%, and 500 units cover $10,000 of fixed costs. https://calculum.dev/blog/are-mortgage-discount-points-worth-the-cost/ https://calculum.dev/blog/are-mortgage-discount-points-worth-the-cost/ Tue, 03 Nov 2026 00:00:00 GMT One discount point is 1 percent of the loan. Break-even is that cash divided by the monthly payment cut, from the CFPB pair through shorter stays. https://calculum.dev/blog/does-a-biweekly-mortgage-save-time-and-interest/ https://calculum.dev/blog/does-a-biweekly-mortgage-save-time-and-interest/ Tue, 03 Nov 2026 00:00:00 GMT A biweekly plan debits half the monthly payment 26 times a year. Here is the time and interest that 13th payment saves on several loans. https://calculum.dev/blog/how-is-a-pregnancy-due-date-calculated/ https://calculum.dev/blog/how-is-a-pregnancy-due-date-calculated/ Tue, 03 Nov 2026 00:00:00 GMT ACOG dates the estimated due date as 280 days after the first day of the last period. A last period on 15 March 2026 and a 28-day cycle land on 20 December 2026. https://calculum.dev/blog/how-long-does-the-rule-of-72-take-to-double-money/ https://calculum.dev/blog/how-long-does-the-rule-of-72-take-to-double-money/ Tue, 03 Nov 2026 00:00:00 GMT Divide 72 by the annual rate to estimate doubling time. Investor.gov uses 9 percent and about 8 years. The exact compound time sits beside it. https://calculum.dev/blog/how-many-grams-of-protein-should-i-eat-in-a-day/ https://calculum.dev/blog/how-many-grams-of-protein-should-i-eat-in-a-day/ Tue, 03 Nov 2026 00:00:00 GMT The adult protein RDA is 0.8 g per kilogram. At 70 kg that is 56 g, and the card shows the weight as 154.3 lb. At 2,000 kcal the AMDR band is 50 to 175 g. https://calculum.dev/blog/how-much-water-should-i-drink-in-a-day/ https://calculum.dev/blog/how-much-water-should-i-drink-in-a-day/ Tue, 03 Nov 2026 00:00:00 GMT The adult total-water Adequate Intake is 3.7 L for men and 2.7 L for women. On the US card those display as 0.98 gal and 0.71 gal, food moisture included. https://calculum.dev/blog/what-is-a-cap-rate-on-a-rental-property/ https://calculum.dev/blog/what-is-a-cap-rate-on-a-rental-property/ Tue, 03 Nov 2026 00:00:00 GMT Cap rate is net operating income divided by price. The mortgage stays out of the formula. Here are several rentals and the price a rate implies. https://calculum.dev/blog/what-is-my-ideal-body-weight/ https://calculum.dev/blog/what-is-my-ideal-body-weight/ Tue, 03 Nov 2026 00:00:00 GMT Devine ideal weight at 175 cm on the male equation is 70.46 kg, which the US card shows as 155.3 lb. The CDC healthy band at that height is 124.9 to 168.1 lb. https://calculum.dev/blog/what-is-the-present-value-of-a-future-sum/ https://calculum.dev/blog/what-is-the-present-value-of-a-future-sum/ Tue, 03 Nov 2026 00:00:00 GMT Present value is a future sum divided by (1 + rate) raised to the years. A $10,000 sum in 10 years at 5 percent is $6,139.13 in this formula. https://calculum.dev/blog/when-is-my-fertile-window/ https://calculum.dev/blog/when-is-my-fertile-window/ Tue, 03 Nov 2026 00:00:00 GMT On a 28-day cycle that starts 15 March 2026, the ASRM calendar window is 23 March through 28 March. Ovulation is cycle day 14, which is cycle length minus 14. https://calculum.dev/blog/how-do-i-calculate-my-semester-gpa/ https://calculum.dev/blog/how-do-i-calculate-my-semester-gpa/ Mon, 02 Nov 2026 00:00:00 GMT Semester GPA is quality points divided by credit hours. The four-course default is 43.9 points over 13 credits, which the calculator prints as 3.38. https://calculum.dev/blog/how-do-i-split-my-paycheck-with-the-50-30-20-rule/ https://calculum.dev/blog/how-do-i-split-my-paycheck-with-the-50-30-20-rule/ Mon, 02 Nov 2026 00:00:00 GMT The CFPB 50/30/20 split puts half of take-home into needs, 30% into wants, and 20% into savings. On $4,200 that is $2,100, $1,260, and $840. https://calculum.dev/blog/how-many-calories-do-i-need-in-a-day/ https://calculum.dev/blog/how-many-calories-do-i-need-in-a-day/ Mon, 02 Nov 2026 00:00:00 GMT Daily calories are a Mifflin-St Jeor resting number times the PAL you type. At 70 kg, 175 cm, age 35, and PAL 1.75, the male equation is 1,624 kcal at rest and 2,842 kcal for the day. https://calculum.dev/blog/how-much-fencing-do-i-need/ https://calculum.dev/blog/how-much-fencing-do-i-need/ Mon, 02 Nov 2026 00:00:00 GMT Fence bays are the length divided by the panel width, rounded up. Posts add one end post and one post per gate. The 32 m default is 18 panels, 20 posts, and 40 concrete bags. https://calculum.dev/blog/how-much-food-do-i-need-to-cater-a-party/ https://calculum.dev/blog/how-much-food-do-i-need-to-cater-a-party/ Mon, 02 Nov 2026 00:00:00 GMT Main food is guests times the grams you type, times a buffer. The 45-guest default, at 350 g of main and 200 g of sides with a 12% buffer, is 38.9 lb of main and 22.2 lb of sides. https://calculum.dev/blog/how-much-house-can-i-afford/ https://calculum.dev/blog/how-much-house-can-i-afford/ Mon, 02 Nov 2026 00:00:00 GMT The price is the loan a payment can support, plus your down payment. On the $7,500 default, at 6.5% for 30 years with 20% down, that price is $296,645.29. https://calculum.dev/blog/how-much-shelving-material-do-i-need/ https://calculum.dev/blog/how-much-shelving-material-do-i-need/ Mon, 02 Nov 2026 00:00:00 GMT Stock boards are shelf length times the count, plus waste, divided by the board you buy. Six 1.2 m shelves at 10% waste need 26 ft, which is 4 boards of 2.4 m, and 18 brackets. https://calculum.dev/blog/what-heart-rate-zone-should-i-train-in/ https://calculum.dev/blog/what-heart-rate-zone-should-i-train-in/ Mon, 02 Nov 2026 00:00:00 GMT Estimated max heart rate is 220 minus age. At 35 that is 185 bpm, and the calculator's AHA 50 to 85 percent target is 93 to 157 bpm. https://calculum.dev/blog/what-is-cagr-and-how-do-i-calculate-it/ https://calculum.dev/blog/what-is-cagr-and-how-do-i-calculate-it/ Mon, 02 Nov 2026 00:00:00 GMT CAGR is (ending ÷ starting) raised to 1 ÷ years, minus 1. $10,000 growing to $16,105.10 in five years is a 10% compound annual rate. https://calculum.dev/blog/what-is-my-bmi-and-what-does-the-number-mean/ https://calculum.dev/blog/what-is-my-bmi-and-what-does-the-number-mean/ Mon, 02 Nov 2026 00:00:00 GMT BMI is kilograms divided by metres squared. At 175 cm and 70 kg the result is 22.9, in the CDC healthy-weight range for adults 20 and older. It is a screen, not a diagnosis. https://calculum.dev/blog/how-do-i-compare-two-personal-loans/ https://calculum.dev/blog/how-do-i-compare-two-personal-loans/ Sun, 01 Nov 2026 00:00:00 GMT Compare two personal loans by monthly payment times the term, plus upfront fees. On $20,000 the 8.5% four-year loan costs $23,962.37 and beats the 7.8% five-year loan at $24,866.98. https://calculum.dev/blog/how-many-months-of-cash-runway-do-i-have/ https://calculum.dev/blog/how-many-months-of-cash-runway-do-i-have/ Sun, 01 Nov 2026 00:00:00 GMT Cash runway is how many months the bank balance lasts when monthly spending outruns cash revenue. The defaults last 9 months from $240,000, with $70,686.05 still in the account after month 6. https://calculum.dev/blog/how-much-decking-material-should-i-buy/ https://calculum.dev/blog/how-much-decking-material-should-i-buy/ Sun, 01 Nov 2026 00:00:00 GMT Deck boards are the deck width divided into rows of face plus gap, times the run, plus waste. The 6 m by 4 m default is 28 rows and 617.3 ft of board, with 840 fasteners. https://calculum.dev/blog/how-much-is-a-late-invoice-fee/ https://calculum.dev/blog/how-much-is-a-late-invoice-fee/ Sun, 01 Nov 2026 00:00:00 GMT A late invoice fee is simple interest on the unpaid balance plus any fixed charge. The $7,500 default is $7,645.96 after 45 days at 12%, and a 360-day year bills a different interest amount. https://calculum.dev/blog/how-much-should-i-budget-for-a-birthday-party/ https://calculum.dev/blog/how-much-should-i-budget-for-a-birthday-party/ Sun, 01 Nov 2026 00:00:00 GMT A birthday total is the venue, food per guest, activities, and extras. The $1,054 default, $58.56 a guest, and what eight more people change. https://calculum.dev/blog/how-much-wallpaper-do-i-need/ https://calculum.dev/blog/how-much-wallpaper-do-i-need/ Sun, 01 Nov 2026 00:00:00 GMT Wallpaper rolls come from wall drops, not the floor. The 7-roll default, the 10% pattern allowance, and the height that jumps the order to 9. https://calculum.dev/blog/what-does-inflation-do-to-purchasing-power/ https://calculum.dev/blog/what-does-inflation-do-to-purchasing-power/ Sun, 01 Nov 2026 00:00:00 GMT A steady inflation rate shrinks what today's cash buys. $10,000 at 3% for 10 years, the BLS CPI method, and the linear mistake at $7,000. https://calculum.dev/blog/what-is-the-price-per-use-of-this-purchase/ https://calculum.dev/blog/what-is-the-price-per-use-of-this-purchase/ Sun, 01 Nov 2026 00:00:00 GMT Price per use is sticker plus upkeep, divided by expected uses. The $0.68 default, the use count that flips the winner, and the sticker-price mistake. https://calculum.dev/blog/what-size-air-conditioner-for-this-room/ https://calculum.dev/blog/what-size-air-conditioner-for-this-room/ Sun, 01 Nov 2026 00:00:00 GMT This room model is area times a watts rate, then people and appliances. The 3.28 kW default, and why that sketch is not an ACCA Manual J load. https://calculum.dev/blog/which-bank-account-costs-less-after-fees/ https://calculum.dev/blog/which-bank-account-costs-less-after-fees/ Sun, 01 Nov 2026 00:00:00 GMT Compare two accounts as a year of fees and overdraft charges minus interest at the stated APY. On a $5,000 balance the defaults pick Account B, at a net cost of -$175.00 against Account A's $119.00. https://calculum.dev/blog/hire-help-vs-diy-which-is-cheaper/ https://calculum.dev/blog/hire-help-vs-diy-which-is-cheaper/ Sat, 31 Oct 2026 00:00:00 GMT DIY cost is materials plus your hours, then a rework buffer, set against the quote. Here is the $966 default, why $35 an hour flips the job, and the $280 mistake of ignoring time. https://calculum.dev/blog/how-do-i-scale-a-recipe/ https://calculum.dev/blog/how-do-i-scale-a-recipe/ Sat, 31 Oct 2026 00:00:00 GMT Scale an ingredient by new servings over original servings, then round. Here is 250 units to 625 for 10 plates, the 62.5-to-65 rounding bump, and the swapped-servings mistake. https://calculum.dev/blog/how-much-does-a-pet-cost-per-year/ https://calculum.dev/blog/how-much-does-a-pet-cost-per-year/ Sat, 31 Oct 2026 00:00:00 GMT The yearly cost is monthly food and insurance, plus vet, care, and a reserve. Here is the $3,710 default, the $4,910 first year, and why skipping the reserve makes year one look $800 cheaper. https://calculum.dev/blog/how-much-does-parking-cost-per-year/ https://calculum.dev/blog/how-much-does-parking-cost-per-year/ Sat, 31 Oct 2026 00:00:00 GMT Daily parking times days times weeks, compared with twelve monthly passes. Here is the $3,456 daily year, the $3,120 pass, and the 3-day week where paying daily wins. https://calculum.dev/blog/how-much-should-i-budget-for-childcare/ https://calculum.dev/blog/how-much-should-i-budget-for-childcare/ Sat, 31 Oct 2026 00:00:00 GMT Net childcare is the price plus extra work costs, minus benefits and credits. Here is the $1,600 default, the $350 subsidy gap, and why the $1,800 sticker is not the household cost. https://calculum.dev/blog/how-much-should-i-reserve-for-self-employment-tax/ https://calculum.dev/blog/how-much-should-i-reserve-for-self-employment-tax/ Sat, 31 Oct 2026 00:00:00 GMT The reserve is profit times the rate you type. Here is the $1,848 default on $6,600 of profit, the $0 month when expenses win, and why 28% is not the IRS 15.3% SE tax. https://calculum.dev/blog/should-i-consolidate-these-debts/ https://calculum.dev/blog/should-i-consolidate-these-debts/ Sat, 31 Oct 2026 00:00:00 GMT Consolidation turns several balances into one new loan. Here is the $2,752.43 default saving, the cheaper payment that costs $2,347.99 more, and why the CFPB says to check the total. https://calculum.dev/blog/what-does-home-ev-charging-cost/ https://calculum.dev/blog/what-does-home-ev-charging-cost/ Sat, 31 Oct 2026 00:00:00 GMT Home charging is distance times efficiency times loss times the kWh price. Here is the $66.53 default month, the $43.50 EIA-rate month, and what a 10% charging loss adds. https://calculum.dev/blog/what-is-my-take-home-pay-after-deductions/ https://calculum.dev/blog/what-is-my-take-home-pay-after-deductions/ Sat, 31 Oct 2026 00:00:00 GMT Take-home is gross minus the rates and fixed amounts you type. Here is the $3,345 default, the $500 swing when the tax rate moves 10 points, and why 22% is not an IRS bracket. https://calculum.dev/blog/when-does-owning-a-car-beat-rideshare/ https://calculum.dev/blog/when-does-owning-a-car-beat-rideshare/ Sat, 31 Oct 2026 00:00:00 GMT Owning costs a monthly fixed pile plus a per-trip variable. Rideshare is fare times trips. Here is the 36.1-trip break-even, the $672 default month, and the round-trip counting mistake. https://calculum.dev/blog/how-do-i-calculate-board-feet-of-lumber/ https://calculum.dev/blog/how-do-i-calculate-board-feet-of-lumber/ Fri, 30 Oct 2026 00:00:00 GMT A board foot is 144 cubic inches. Here is the 64.9 board-foot default pack, why a nominal 2x6 order jumps to 96, and the 30-board-foot miss from using the stamp instead of the tape. https://calculum.dev/blog/how-is-a-gas-bill-estimated/ https://calculum.dev/blog/how-is-a-gas-bill-estimated/ Fri, 30 Oct 2026 00:00:00 GMT A gas bill is usage times the unit rate, plus the daily standing charge, then tax. Here is the $94.50 default month, why a winter 1,800 kWh month is $184.28, and the $14.18 you still pay at zero use. https://calculum.dev/blog/how-much-can-led-bulbs-save/ https://calculum.dev/blog/how-much-can-led-bulbs-save/ Fri, 30 Oct 2026 00:00:00 GMT LED savings are the watts you drop, times hours, times the kWh price. Here is the $196.57 default year on 12 bulbs, why 8-hour rooms double that, and the $23 leftover when you start from a CFL. https://calculum.dev/blog/how-much-is-a-personal-loan-payment/ https://calculum.dev/blog/how-much-is-a-personal-loan-payment/ Fri, 30 Oct 2026 00:00:00 GMT A personal-loan payment is the amortizing amount on principal, rate, and term. Here is the $376.85 default, $3,088.66 of interest, and why a longer term costs more. https://calculum.dev/blog/how-much-should-i-budget-for-car-maintenance/ https://calculum.dev/blog/how-much-should-i-budget-for-car-maintenance/ Fri, 30 Oct 2026 00:00:00 GMT A car maintenance fund is scheduled service, repairs, and registration, plus a buffer, then divided by 12. Here is the $165.79 default, a $76 newer-car path, and the $17 miss if you drop inspection. https://calculum.dev/blog/how-much-should-i-save-for-new-tires/ https://calculum.dev/blog/how-much-should-i-save-for-new-tires/ Fri, 30 Oct 2026 00:00:00 GMT A tire reserve is set cost times monthly distance divided by tire life, plus seasonal storage divided by 12. Here is the $41.87 default and the $25.20 path without changeover. https://calculum.dev/blog/what-does-food-waste-cost-each-year/ https://calculum.dev/blog/what-does-food-waste-cost-each-year/ Fri, 30 Oct 2026 00:00:00 GMT Food-waste cost is weekly spending times the waste share times 52, plus a year of disposal fees. Here is the $1,219.20 default, the $561.60 save if waste halves, and the $96 disposal line people skip. https://calculum.dev/blog/what-does-time-of-use-electricity-cost/ https://calculum.dev/blog/what-does-time-of-use-electricity-cost/ Fri, 30 Oct 2026 00:00:00 GMT Time-of-use cost is peak kWh times the peak price, plus off-peak kWh times the night price, plus the fixed charge. Here is the $153 default month and the $20 shift. https://calculum.dev/blog/what-is-my-loan-to-value-ratio/ https://calculum.dev/blog/what-is-my-loan-to-value-ratio/ Fri, 30 Oct 2026 00:00:00 GMT Loan-to-value is the loan balance divided by the current asset value. Here is the 76.2% default, the 80% line where PMI can start, and how a 10% price drop lifts LTV by more than 10 points. https://calculum.dev/blog/when-does-a-transit-pass-beat-single-tickets/ https://calculum.dev/blog/when-does-a-transit-pass-beat-single-tickets/ Fri, 30 Oct 2026 00:00:00 GMT A pass breaks even when you ride often enough to cover its price at the single fare. Here is the 34-ride default, why 20 rides lose $45, and the 22-ride miss from counting a round trip as one fare. https://calculum.dev/blog/car-vs-train-vs-flight-which-trip-is-cheaper/ https://calculum.dev/blog/car-vs-train-vs-flight-which-trip-is-cheaper/ Thu, 29 Oct 2026 00:00:00 GMT Compare party cost and door-to-door time. Here is the $290 train default, why a fourth seat flips the winner to the car, and the fuel-only mistake that prints $111.96. https://calculum.dev/blog/how-do-i-convert-weekly-pay-to-annual-salary/ https://calculum.dev/blog/how-do-i-convert-weekly-pay-to-annual-salary/ Thu, 29 Oct 2026 00:00:00 GMT Weekly pay times 52 is the IRS annual figure. Here is the period table, a $1,200 week that is $62,400 a year, and the $4,800 error from treating biweekly as twice a month. https://calculum.dev/blog/how-do-overtime-hours-change-this-weeks-pay/ https://calculum.dev/blog/how-do-overtime-hours-change-this-weeks-pay/ Thu, 29 Oct 2026 00:00:00 GMT Paid hours are shift time minus unpaid breaks. Here is the 39.5-hour $987.50 default, the 7.5-hour overtime week at $1,281.25, and the mistake that counts 42 hours as paid. https://calculum.dev/blog/how-much-does-homemade-coffee-cost-per-cup/ https://calculum.dev/blog/how-much-does-homemade-coffee-cost-per-cup/ Thu, 29 Oct 2026 00:00:00 GMT Bag price divided by grams, times the dose, plus milk and equipment. Here is the $1.50 default cup, a $0.92 grocery-price cup, and the $0.95 beans-only mistake. https://calculum.dev/blog/how-much-home-equity-do-i-have/ https://calculum.dev/blog/how-much-home-equity-do-i-have/ Thu, 29 Oct 2026 00:00:00 GMT Gross equity is value minus secured debt. Here is the $160,000 default, the $28,800 sale-cost haircut, and why a 10% price drop cuts net equity by more than 10%. https://calculum.dev/blog/how-much-roofing-material-do-i-need/ https://calculum.dev/blog/how-much-roofing-material-do-i-need/ Thu, 29 Oct 2026 00:00:00 GMT Roofing is sold by the square and the bundle. Here is the 51-bundle default, why a 12/12 pitch adds 13 bundles, and the 11-bundle miss from ordering off the footprint alone. https://calculum.dev/blog/how-much-should-i-budget-for-a-trip/ https://calculum.dev/blog/how-much-should-i-budget-for-a-trip/ Thu, 29 Oct 2026 00:00:00 GMT Add transport, lodging, food, activities, and insurance, then a buffer. Here is the $3,225.60 default, eight worked trips, and why a 0% buffer is the usual miss. https://calculum.dev/blog/how-much-should-i-put-in-a-sinking-fund-each-month/ https://calculum.dev/blog/how-much-should-i-put-in-a-sinking-fund-each-month/ Thu, 29 Oct 2026 00:00:00 GMT A sinking fund is the remaining cost, divided by the months left. Here is the $200 default, the $400 rush if the deadline halves, and the $40 error from ignoring cash already saved. https://calculum.dev/blog/what-does-a-hotel-stay-actually-cost/ https://calculum.dev/blog/what-does-a-hotel-stay-actually-cost/ Thu, 29 Oct 2026 00:00:00 GMT Nightly rate plus lodging tax, resort fees, and one-time charges. Here is the $1,211 default, the $180 headline that hides $242.20 a night, and why two nights cost $255.70 each. https://calculum.dev/blog/when-does-refinancing-a-mortgage-break-even/ https://calculum.dev/blog/when-does-refinancing-a-mortgage-break-even/ Thu, 29 Oct 2026 00:00:00 GMT Break-even is refinancing costs divided by the monthly payment cut. Here is the 24-month default, the 104-month $50 cut, and why a higher 15-year payment has no payment break-even. https://calculum.dev/blog/how-much-drywall-do-i-need-for-a-room/ https://calculum.dev/blog/how-much-drywall-do-i-need-for-a-room/ Wed, 28 Oct 2026 00:00:00 GMT Drywall is sold by the sheet. Here is the wall-area formula, a 15-sheet default room, and why 5% and 10% waste can buy the same count. https://calculum.dev/blog/what-is-the-true-cost-of-an-internet-plan/ https://calculum.dev/blog/what-is-the-true-cost-of-an-internet-plan/ Wed, 28 Oct 2026 00:00:00 GMT The advertised month is not the year. Here is the promo-plus-regular-plus-fees formula, a $67.50 effective default, and why a 12-month teaser hides a $1,620 two-year bill. https://calculum.dev/blog/when-do-solar-panels-pay-for-themselves/ https://calculum.dev/blog/when-do-solar-panels-pay-for-themselves/ Wed, 28 Oct 2026 00:00:00 GMT Solar payback is net system cost divided by the yearly bill value of generation. Here is the 7.6-year default, what a rebate does, and why exported kWh stretch the date. https://calculum.dev/blog/how-much-should-i-save-for-a-down-payment/ https://calculum.dev/blog/how-much-should-i-save-for-a-down-payment/ Tue, 27 Oct 2026 00:00:00 GMT Cash to close is the down payment plus closing costs and prepaids, minus credits. Here is the $96,100 default, four down-payment sizes, and the monthly deposit that hits the date. https://calculum.dev/blog/how-much-should-i-set-aside-for-home-maintenance/ https://calculum.dev/blog/how-much-should-i-set-aside-for-home-maintenance/ Tue, 27 Oct 2026 00:00:00 GMT A maintenance reserve is a percent of home value, raised for an older house, then divided by 12. Here is the $483 default, the CFPB 1% rule of thumb, and how a renovation contingency sits on top. https://calculum.dev/blog/what-does-a-grocery-price-increase-cost-over-a-year/ https://calculum.dev/blog/what-does-a-grocery-price-increase-cost-over-a-year/ Tue, 27 Oct 2026 00:00:00 GMT A grocery increase is the new basket minus the old one, times trips, times 12. Here is the $145 to $158 default, the $624 yearly gap, and how that change hits a $4,200 month. https://calculum.dev/blog/how-do-i-calculate-net-worth/ https://calculum.dev/blog/how-do-i-calculate-net-worth/ Mon, 26 Oct 2026 00:00:00 GMT Net worth is assets minus debts. Here is the $163,000 default snapshot, why home equity is not cash, and how a 20.2% savings rate moves the number. https://calculum.dev/blog/how-much-does-a-meeting-cost-the-company/ https://calculum.dev/blog/how-much-does-a-meeting-cost-the-company/ Mon, 26 Oct 2026 00:00:00 GMT A meeting costs attendees times loaded hourly pay times duration. Here is the $494.79 default, what a weekly hour costs over a year, and why 25% overhead is not the BLS benefits share. https://calculum.dev/blog/how-much-does-a-raise-change-take-home-pay/ https://calculum.dev/blog/how-much-does-a-raise-change-take-home-pay/ Mon, 26 Oct 2026 00:00:00 GMT A 7% raise on $72,000 is $5,040 gross. Here is the estimated $302.40 extra per month after a 28% deduction rate, and why that rate is not an IRS table. https://calculum.dev/blog/how-much-should-i-save-for-a-wedding/ https://calculum.dev/blog/how-much-should-i-save-for-a-wedding/ Sun, 25 Oct 2026 00:00:00 GMT A wedding savings number is the guest budget after fixed costs and a contingency. Here is the $30,000 default, $133.33 per guest, and the monthly deposit that actually hits the date. https://calculum.dev/blog/lease-vs-buy-a-car/ https://calculum.dev/blog/lease-vs-buy-a-car/ Sun, 25 Oct 2026 00:00:00 GMT Lease versus buy is a term-and-resale question. Here is the calculator formula, the $22,220 versus $16,600 default, and why a lower monthly payment can still cost more. https://calculum.dev/blog/what-is-my-one-rep-max/ https://calculum.dev/blog/what-is-my-one-rep-max/ Sun, 25 Oct 2026 00:00:00 GMT A one-rep max estimate averages the Epley and Brzycki formulas. Here is the 80 kg for 5 reps default, the 202.1 lb US display, and why sets past 10 reps are a weak input. https://calculum.dev/blog/how-do-i-calculate-percentage-increase/ https://calculum.dev/blog/how-do-i-calculate-percentage-increase/ Sat, 24 Oct 2026 00:00:00 GMT Percentage increase is (new minus old) divided by old. Here is the 80-to-100 example that prints 25%, the reverse-price question, and why stacked discounts are not 20 plus 10. https://calculum.dev/blog/how-long-to-repay-a-student-loan-at-this-payment/ https://calculum.dev/blog/how-long-to-repay-a-student-loan-at-this-payment/ Sat, 24 Oct 2026 00:00:00 GMT A student loan payoff date is the remaining balance, the rate, and the payment you actually send. Here is the $25,000 default path, a 10-year labeled example, and what an extra $100 does. https://calculum.dev/blog/when-does-a-heat-pump-pay-for-itself/ https://calculum.dev/blog/when-does-a-heat-pump-pay-for-itself/ Sat, 24 Oct 2026 00:00:00 GMT Heat pump payback is net install cost divided by yearly heating savings. Here is the 7.6-year default, what a rebate does, and why a cheap furnace bill stretches the date. https://calculum.dev/blog/how-much-concrete-do-i-need-for-a-slab/ https://calculum.dev/blog/how-much-concrete-do-i-need-for-a-slab/ Fri, 23 Oct 2026 00:00:00 GMT Concrete volume is length times width times depth, then a waste allowance. Here is the 1.944 m³ default slab, why 8% waste buys 162 bags at 0.012 m³, and how a thicker pour changes the order. https://calculum.dev/blog/how-much-do-i-save-by-working-from-home/ https://calculum.dev/blog/how-much-do-i-save-by-working-from-home/ Fri, 23 Oct 2026 00:00:00 GMT A home day saves commute and food, then loses extra utilities and equipment. Here is the $3,144 default year, a hybrid week, and why a home-office deduction is a different number. https://calculum.dev/blog/how-much-life-insurance-do-i-need/ https://calculum.dev/blog/how-much-life-insurance-do-i-need/ Fri, 23 Oct 2026 00:00:00 GMT Life insurance needs are income support plus debts and future costs, minus assets already there. Here is the $874,000 default gap, and why a 5-to-8 times income rule can miss. https://calculum.dev/blog/how-much-does-it-cost-to-move/ https://calculum.dev/blog/how-much-does-it-cost-to-move/ Thu, 22 Oct 2026 00:00:00 GMT A move is transport, supplies, travel, and setup, plus a contingency. Here is the $3,432 default budget, a 12% buffer walkthrough, and the extra cash a new lease asks for. https://calculum.dev/blog/markup-vs-margin-what-selling-price-do-i-need/ https://calculum.dev/blog/markup-vs-margin-what-selling-price-do-i-need/ Thu, 22 Oct 2026 00:00:00 GMT Margin is profit divided by selling price. Markup is profit divided by cost. Here is why a 35% margin on a $65 cost is a $100 price, not a 35% markup. https://calculum.dev/blog/what-is-the-true-cost-of-owning-a-car/ https://calculum.dev/blog/what-is-the-true-cost-of-owning-a-car/ Thu, 22 Oct 2026 00:00:00 GMT True car cost is depreciation plus interest, insurance, fuel, and upkeep. Here is the $12,500 default year, the loan next to it, and how that compares with the IRS mileage rate. https://calculum.dev/blog/how-much-does-a-shower-cost/ https://calculum.dev/blog/how-much-does-a-shower-cost/ Wed, 21 Oct 2026 00:00:00 GMT A shower costs the water you use plus the energy that heats it. Here is the litre-and-kWh formula, a 9-minute example, and what a shorter shower or a 2.0 gpm head changes. https://calculum.dev/blog/how-much-does-this-appliance-add-to-the-electric-bill/ https://calculum.dev/blog/how-much-does-this-appliance-add-to-the-electric-bill/ Wed, 21 Oct 2026 00:00:00 GMT Appliance cost is watts times hours times your kWh price. Here is the formula, a 1,200-watt example, and how standby draw compares with a heater you leave on. https://calculum.dev/blog/which-package-is-cheaper-per-unit/ https://calculum.dev/blog/which-package-is-cheaper-per-unit/ Wed, 21 Oct 2026 00:00:00 GMT Unit price is the sticker divided by the amount in the pack. Here is the formula, an $8.49 versus $11.99 example, and when a bigger pack still costs more after waste. https://calculum.dev/blog/50-30-20-budget-vs-leftover-after-bills/ https://calculum.dev/blog/50-30-20-budget-vs-leftover-after-bills/ Tue, 20 Oct 2026 00:00:00 GMT The 50/30/20 rule splits take-home pay into needs, wants, and saving. Here is how that grid compares with leftover after the bills you already pay. https://calculum.dev/blog/how-much-do-i-need-to-save-each-month-for-a-goal/ https://calculum.dev/blog/how-much-do-i-need-to-save-each-month-for-a-goal/ Tue, 20 Oct 2026 00:00:00 GMT A monthly savings number is the gap to the target, filled by deposits and a return you choose. Here is the timeline formula, a $25,000 example, and the 0% cash baseline. https://calculum.dev/blog/should-extra-money-repay-the-mortgage-or-go-into-an-index-fund/ https://calculum.dev/blog/should-extra-money-repay-the-mortgage-or-go-into-an-index-fund/ Tue, 20 Oct 2026 00:00:00 GMT Extra mortgage principal buys a predictable interest saving. The same cash in an index fund may grow more, or less. Here is the calculator comparison at the published defaults. https://calculum.dev/blog/how-does-compound-interest-grow-savings/ https://calculum.dev/blog/how-does-compound-interest-grow-savings/ Mon, 19 Oct 2026 00:00:00 GMT Compound interest is interest paid on principal and on interest already earned. Here is the SEC definition, a 10-year worked example, and what fees take out of the ending balance. https://calculum.dev/blog/how-much-does-my-commute-actually-cost/ https://calculum.dev/blog/how-much-does-my-commute-actually-cost/ Mon, 19 Oct 2026 00:00:00 GMT Commute cost is distance times a vehicle rate, plus parking, times the days you actually go. Here is the formula, a 42 km worked example, and what hybrid and bicycle days change. https://calculum.dev/blog/what-does-a-rent-increase-cost-over-the-lease/ https://calculum.dev/blog/what-does-a-rent-increase-cost-over-the-lease/ Mon, 19 Oct 2026 00:00:00 GMT A rent increase is the new monthly rent minus the old one, times the months you will pay it. Here is the formula, a $1,500 to $1,625 example, and how that change hits a budget. https://calculum.dev/blog/how-much-does-a-road-trip-cost-in-fuel/ https://calculum.dev/blog/how-much-does-a-road-trip-cost-in-fuel/ Sun, 18 Oct 2026 00:00:00 GMT Fuel cost is distance times consumption times price. Here is the formula, an 850 km worked example, and how sharing the tank changes each person's bill. https://calculum.dev/blog/how-much-flooring-should-i-buy/ https://calculum.dev/blog/how-much-flooring-should-i-buy/ Sun, 18 Oct 2026 00:00:00 GMT Flooring is sold by the pack. Here is the waste-and-pack formula, a 5.2 by 3.8 metre room, and why 5% and 10% waste can buy the same number of packs. https://calculum.dev/blog/what-hourly-rate-should-a-freelancer-charge/ https://calculum.dev/blog/what-hourly-rate-should-a-freelancer-charge/ Sun, 18 Oct 2026 00:00:00 GMT A freelance rate has to cover unpaid hours, overhead, and a tax buffer. Here is the formula, an $80,000 target, and why salary divided by 2,080 is the wrong quote. https://calculum.dev/blog/how-do-i-convert-salary-to-hourly-pay/ https://calculum.dev/blog/how-do-i-convert-salary-to-hourly-pay/ Sat, 17 Oct 2026 00:00:00 GMT Salary divided by 2,080 hours is a payroll shortcut. Here is the working-weeks formula, a $72,000 example, and why unpaid overtime changes the hourly number. https://calculum.dev/blog/how-much-should-i-tip/ https://calculum.dev/blog/how-much-should-i-tip/ Sat, 17 Oct 2026 00:00:00 GMT There is no official US tip percentage. Here is the pre-tax formula, a $146 bill split three ways, and what the IRS and DOL actually say about tips. https://calculum.dev/blog/how-should-roommates-split-rent-fairly/ https://calculum.dev/blog/how-should-roommates-split-rent-fairly/ Sat, 17 Oct 2026 00:00:00 GMT Equal rent is the average. Here is the floor-area split, a $3,600 three-roommate example, and how a shared security deposit comes back after deductions. https://calculum.dev/blog/how-much-do-my-subscriptions-cost-per-year/ https://calculum.dev/blog/how-much-do-my-subscriptions-cost-per-year/ Fri, 16 Oct 2026 00:00:00 GMT Monthly charges hide the yearly bill. Here is the sum-times-12 formula, a five-service worked example, and when buying once costs less than another year of the same app. https://calculum.dev/blog/how-much-paint-do-i-need-for-a-room/ https://calculum.dev/blog/how-much-paint-do-i-need-for-a-room/ Fri, 16 Oct 2026 00:00:00 GMT Floor area is the wrong number for walls. Here is the wall-area formula, a worked room, and how to turn the coverage on the can into litres or gallons. https://calculum.dev/blog/should-i-rent-or-buy-this-house/ https://calculum.dev/blog/should-i-rent-or-buy-this-house/ Fri, 16 Oct 2026 00:00:00 GMT Rent versus buy is a time-horizon question. Here is the calculator formula, a five-year worked example, and the cash you need before the monthly payment even starts. https://calculum.dev/blog/what-is-a-good-debt-to-income-ratio/ https://calculum.dev/blog/what-is-a-good-debt-to-income-ratio/ Fri, 16 Oct 2026 00:00:00 GMT DTI is monthly debt divided by gross monthly income. Here is the CFPB definition, their 33% example, and how a mortgage or a card payment moves the number. https://calculum.dev/blog/debt-snowball-vs-avalanche-which-costs-less/ https://calculum.dev/blog/debt-snowball-vs-avalanche-which-costs-less/ Thu, 15 Oct 2026 00:00:00 GMT Avalanche sends extra money to the highest APR first. Snowball sends it to the smallest balance. Here is the same two-debt plan run both ways, with the interest each order costs. https://calculum.dev/blog/how-is-a-mortgage-payment-calculated/ https://calculum.dev/blog/how-is-a-mortgage-payment-calculated/ Wed, 14 Oct 2026 00:00:00 GMT Lenders set principal and interest so the loan hits zero on the last payment. Here is the formula, a worked example, and what taxes and insurance add on top. https://calculum.dev/blog/how-long-will-it-take-to-pay-off-my-credit-card/ https://calculum.dev/blog/how-long-will-it-take-to-pay-off-my-credit-card/ Tue, 13 Oct 2026 00:00:00 GMT A payment only starts shrinking the balance after it covers that month's interest. Here is how to turn a card balance, APR, and payment into a payoff date. https://calculum.dev/blog/how-much-should-i-have-in-an-emergency-fund/ https://calculum.dev/blog/how-much-should-i-have-in-an-emergency-fund/ Mon, 12 Oct 2026 00:00:00 GMT Three to six months of essential bills is the usual range. Here is how to turn housing, food, and debt payments into a cash target you can fund. https://calculum.dev/blog/how-much-rent-can-i-afford/ https://calculum.dev/blog/how-much-rent-can-i-afford/ Sun, 11 Oct 2026 00:00:00 GMT The 30% rent rule is a US housing-policy line, not a personal budget. Here is how to turn take-home pay, debts, and savings into a rent you can live with.