Air Conditioner BTU Calculator
Estimates the BTU or kilowatt cooling capacity needed to size an air conditioner for a room.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the room area, ceiling height, usual occupants and a sun adjustment.
- Read the estimated BTU/h and kW.
How it works
Starts at ~150 BTU/m², scales for ceiling height, adds for extra occupants and a sun factor. A rough sizing guide only.
Worked example
25 m², 2.4 m, 2 people, +10% sun. ≈ 4.1 kW of cooling.
Tips
- Runs entirely in your browser. Your inputs are not saved or transmitted.
Frequently asked questions
Is this exact?
No — it's a ballpark. A proper heat-load calculation considers insulation, windows and climate.
Privacy?
Runs entirely in your browser. Your inputs are not saved or transmitted.
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Cite this tool
Zerdly. (2026). Air Conditioner BTU Calculator. Retrieved from https://www.zerdly.com/tools/ac-btu-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.