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Quick answer
What does the Air-conditioner room sizing calculate?
What approximate cooling capacity does your room need? This calculator uses room length, room width, base cooling capacity per area, sun, glazing, and insulation adjustment, additional occupants beyond two, cooling load per additional occupant, and lighting and appliance cooling load to estimate approximate room cooling load immediately in your browser.
With the values currently entered, the result is 3.28 kW — approximate cooling capacity. It also shows cooling capacity, room area, planning range, and occupant and appliance load.
How to use the Air-conditioner room sizing
- 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
- Room length — entered in m
- Room width — entered in m
- Base cooling capacity per area — entered in W/m²
- Sun, glazing, and insulation adjustment — entered in %
- Additional occupants beyond two — entered in people
- Cooling load per additional occupant — entered in W
- Lighting and appliance cooling load — entered in W
Air-conditioner room sizing formula
Area × entered watts per area × room adjustment + additional occupant and appliance loads
Assumptions
- The base capacity and percentage adjustment reflect the climate and room conditions you intend to model.
- Standard ceiling height is assumed; humidity, ventilation, ducts, infiltration, and adjacent spaces are not modeled.
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
Air-conditioner room sizing example and edge cases
What approximate cooling capacity does your room need? Let's use a concrete example, then look at the assumptions that can move the answer.
Example: A practical air-conditioner room sizing scenario
For this example, use room length of 5 m, room width of 4 m, base cooling capacity per area of 125 W/m², sun, glazing, and insulation adjustment of 15 %, additional occupants beyond two of 1 people, cooling load per additional occupant of 100 W, and lighting and appliance cooling load of 300 W. These are starting values, so replace them with numbers that match your situation.
- Room length
- 5 m
- Room width
- 4 m
- Base cooling capacity per area
- 125 W/m²
- Sun, glazing, and insulation adjustment
- 15 %
- Additional occupants beyond two
- 1 people
- Cooling load per additional occupant
- 100 W
- Lighting and appliance cooling load
- 300 W
Calculated result3.28 kWapproximate cooling capacity
Start with approximate cooling capacity. Then check cooling capacity, room area, planning range, and occupant and appliance load 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 cooling capacity, room area, planning range, and occupant and appliance load explain how the estimate is built.
- The method is Area × entered watts per area × room adjustment + additional occupant and appliance loads. Keep the units consistent and use values from the same time period.
Edge cases worth checking
When room length is unusual
The base capacity and percentage adjustment reflect the climate and room conditions you intend to model. Double-check this input before relying on the result.
When lighting and appliance cooling load is uncertain
Standard ceiling height is assumed; humidity, ventilation, ducts, infiltration, and adjacent spaces are not modeled. Run a lower and higher value to see a useful range.
What changes the result most
Room length
Measure room length with the same unit shown beside the input. Convert first if your source uses another unit.
Room width
Measure room width with the same unit shown beside the input. Convert first if your source uses another unit.
Base cooling capacity per area
Measure base cooling capacity per area with the same unit shown beside the input. Convert first if your source uses another unit.
Try a different scenario
Small changes show whether the answer is stable or sensitive.
Room length: 10% lower
5 m3.28 kWapproximate cooling capacity
Room length: 10% higher
6 m3.85 kWapproximate cooling capacity
Room width: 10% higher
4 m3.28 kWapproximate cooling capacity
Common mistakes
Check room length
The base capacity and percentage adjustment reflect the climate and room conditions you intend to model. Make sure this matches the number you enter.
Keep lighting and appliance cooling load consistent
Standard ceiling height is assumed; humidity, ventilation, ducts, infiltration, and adjacent spaces are not modeled. Use the same units and time period throughout the calculation.
Do not rely on one air-conditioner room sizing scenario
Run a cautious case and an optimistic case. The range is often more useful than one exact-looking number.
Use this result well
What approximate cooling capacity does your room need?
Actual tariffs, weather, equipment behavior, and fixed charges can change the bill.