Building tool
HVAC BTU Calculator
Estimate room cooling or heating BTU from area, ceiling, climate, windows, and occupants.
Runs in your browserResult
- Estimated capacity
- 13,000 BTU/hr
- Nominal tons
- 1.08
- Rounded common size
- 18,000 BTU/hr
- Airflow rule of thumb
- 433 CFM
This is a quick sizing estimate, not a Manual J load calculation. Insulation, leakage, orientation, humidity, ducts, climate, and equipment performance matter.
How to use this HVAC btu calculator
- Enter the conditioned area, ceiling or climate details, and the heat-load adjustments shown in the form.
- Review the calculated totals, units, and assumptions. Check the inputs and units before relying on the result.
- Change one input at a time to compare another case, then copy or save the result you plan to use.
About this HVAC btu calculator
The HVAC BTU Calculator lets you estimate room cooling or heating BTU from area, ceiling, climate, windows, and occupants. The controls cover only the inputs needed for the result.
You can also use it to compare results after changing one input.
Example
Use the HVAC BTU Calculator for a 1,500 square foot conditioned space, then adjust for climate, ceiling height, windows, and occupancy.
Common uses
- → estimate room cooling or heating BTU from area, ceiling, climate, windows, and occupants
- → compare results after changing one input
- → save an estimate for planning or comparison