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What does the Retirement income runway calculate?
How long can retirement savings support the income gap you expect? This calculator uses retirement savings, monthly spending, monthly pension or other income, and annual return after fees to estimate savings withdrawal runway immediately in your browser.
With the values currently entered, the result is 47y 7m — estimated savings runway. It also shows monthly spending gap, first-year drawdown, and balance after 10 years.
How to use the Retirement income runway
- Replace the example values with your own numbers.
- Review the result and supporting figures as they update automatically.
- Check the formula and assumptions before using the estimate for a decision.
Inputs used
- Retirement savings
- Monthly spending
- Monthly pension or other income
- Annual return after fees — entered in %
Retirement income runway formula
Each month: balance × (1 + annual return ÷ 12) − spending gap
Assumptions
- Spending, other income, and return stay constant before inflation.
- Withdrawals happen at the end of each month and taxes are excluded.
Verify the inputs
Authoritative sources
These sources explain the definitions, factors, or rules behind this tool. Their geographic scope is shown because an official source for one country is not automatically valid somewhere else.
Sources do not endorse Calculum. Check the source date, scope, and your own documents before making a financial, tax, insurance, or reporting decision.
Practical guide
Retirement income runway example and edge cases
How long can retirement savings support the income gap you expect? Let's use a concrete example, then look at the assumptions that can move the answer.
Example: A practical retirement income runway scenario
For this example, use retirement savings of 500,000, monthly spending of 4,000, monthly pension or other income of 2,200, and annual return after fees of 3.5 %. These are starting values, so replace them with numbers that match your situation.
- Retirement savings
- 500,000
- Monthly spending
- 4,000
- Monthly pension or other income
- 2,200
- Annual return after fees
- 3.5 %
Calculated result47y 7mestimated savings runway
Start with estimated savings runway. Then check monthly spending gap, first-year drawdown, and balance after 10 years to understand what sits behind the main result.
Example results use the default display profile. The calculator above follows your selected country and units.
How to read the result
- Read the main result first. The supporting figures for monthly spending gap, first-year drawdown, and balance after 10 years explain how the estimate is built.
- The method is Each month: balance × (1 + annual return ÷ 12) − spending gap. Keep the units consistent and use values from the same time period.
Edge cases worth checking
When retirement savings is unusual
Spending, other income, and return stay constant before inflation. Double-check this input before relying on the result.
When annual return after fees is uncertain
Withdrawals happen at the end of each month and taxes are excluded. Run a lower and higher value to see a useful range.
What changes the result most
Retirement savings
Use a current amount for retirement savings. Include fees or recurring costs that belong in the same figure.
Monthly spending
Use a current amount for monthly spending. Include fees or recurring costs that belong in the same figure.
Monthly pension or other income
Use a current amount for monthly pension or other income. Include fees or recurring costs that belong in the same figure.
Try a different scenario
Small changes show whether the answer is stable or sensitive.
Retirement savings: 10% lower
450,00037y 5mestimated savings runway
Retirement savings: 10% higher
550,00063y 6mestimated savings runway
Monthly spending: 10% higher
4,40031y 2mestimated savings runway
Common mistakes
Check retirement savings
Spending, other income, and return stay constant before inflation. Make sure this matches the number you enter.
Keep annual return after fees consistent
Withdrawals happen at the end of each month and taxes are excluded. Use the same units and time period throughout the calculation.
Do not rely on one retirement income runway scenario
Run a cautious case and an optimistic case. The range is often more useful than one exact-looking number.
Use this result well
How long can retirement savings support the income gap you expect?
It is a planning estimate, not a forecast or personal financial advice.