BTU Calculator
Estimate the heating or cooling capacity needed for a room.
Result
Required capacity
8,500 BTU/hr
Cooling tons
0.71 ton
This is a simple rule-of-thumb estimate, not a substitute for a professional ACCA Manual J load calculation. Get a professional assessment before actual installation.
Usage examples
Estimating AC capacity for a new room
Enter the room's area, insulation level, and window count to quickly estimate roughly how many BTU of AC capacity you'll need.
Accounting for heat-heavy spaces like a kitchen
Check the kitchen box to factor in the extra heat load from cooking appliances, for a more realistic estimate.
Comparing against real product specs before buying
Compare the calculated BTU/hr and tonnage against the specs of AC units or heaters you're considering, as a reference for picking the right capacity.
Frequently asked questions
Can I rely on this result to buy a unit?
No. This calculator is a simple rule-of-thumb starting point based on a basic heuristic. Get a proper load calculation like ACCA Manual J, or a professional on-site assessment, before actual installation.
Can I use m² instead of sq ft?
Input is in sq ft. Multiply your m² value by 10.764 to convert to sq ft.
Why does ceiling height affect the result?
A ceiling taller than the standard 8ft means more air volume to heat or cool, so the required capacity is scaled up accordingly.
How many BTU is one ton?
In cooling capacity, one ton equals 12,000 BTU/hr. Residential AC units are often labeled in tons as well.