BTU / air conditioner sizing calculator

This calculator estimates the cooling capacity, in BTU per hour, for a room window air conditioner in the United States. It follows the EPA ENERGY STAR room air conditioner method. It is not a whole-house or central air-conditioning calculation, and it does not use ACCA Manual J.

Room area

Length (feet) Width (feet)

Sunlight

People who regularly occupy the room ENERGY STAR adds 600 BTU for each person beyond two.

Is the unit used in a kitchen?

Ceiling height The ENERGY STAR capacities assume an 8-foot ceiling. This calculator does not apply an extra ceiling-height factor.

How the BTU / air conditioner sizing calculator works

Results from these calculators are for learning and estimation only. They are not a substitute for a licensed electrician, a licensed HVAC contractor, the local codebook, or manufacturer instructions. The electrical tools use a DC-resistance method and do not calculate ampacity, derating, conduit fill, reactance, or power factor. The BTU tool is only for U.S. room window air conditioners, not central systems, and does not replace a professional load calculation. The methods are written for U.S. practice and are not directly applicable outside the United States. If you use these results, you do so at your own risk.