BTU Calculator (AC)
Estimate the cooling BTU needed for a room.
Result
Results are estimates for general information only and are not professional advice.
Sizing an air conditioner
A common rule of thumb is about 20 BTU of cooling per square foot of room area. This calculator estimates the BTU rating you need; adjust upward for sunny rooms, high ceilings or many occupants.
Frequently Asked Questions
What is the BTU Calculator (AC)?
Estimate the cooling BTU needed for a room. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the BTU Calculator (AC)?
The BTU Calculator (AC) asks for a single value: Room area (sq ft). Enter it and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the BTU Calculator (AC)?
The BTU Calculator (AC) uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the BTU Calculator (AC) free, and do I need an account?
Yes. The BTU Calculator (AC) — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.