About BTU Calculator
A BTU per hour (BTU/h) is the unit used to rate air conditioner cooling capacity. This calculator uses a rule of thumb: 600 BTU/h per m² of floor area for a 3 m ceiling, scaled by ceiling height ÷ 3, plus 600 BTU/h for each person beyond two, and 10% more for a sunny room. It converts the result with 1 ton of refrigeration = 12,000 BTU/h and 1 kW = 3,412 BTU/h. A professional load calculation is more precise.
How to use BTU Calculator
- Fill in "Room length", "Room width", "Ceiling height" and "Number of people", and the other options.
- The result appears below and updates as you type.
- Copy the result with the copy button, or download it as a file where that is offered.
Questions about BTU Calculator
How many BTU is a 1 ton air conditioner?
One ton of refrigeration equals 12,000 BTU per hour, or about 3.5 kW of cooling. A 1.5 ton unit is 18,000 BTU/h and a 2 ton unit is 24,000 BTU/h.
Is a bigger air conditioner always better?
No. An oversized unit cools the air quickly and switches off before it has removed much humidity, which leaves the room clammy and wastes energy. Choose the size closest to the calculated load.
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