Calculators
BTU Calculator
Estimate the BTU capacity a room needs.
FreeNo sign-upWorks in your browser
Enter details
Result
Cooling capacity needed
6,000 BTU/hr
~20 BTU per sq ft
Heating capacity
10,500 BTU/hr
~30–40 BTU per sq ft
About the BTU Calculator
Sizing an air conditioner or heater? Enter the room's square footage and the calculator estimates the cooling capacity (about 20 BTU per square foot) and heating capacity you need. Right-sizing keeps a room comfortable and your energy bills down.
How to use the BTU Calculator
- 1Enter your room square footage.
- 2Read the result instantly — it recalculates as you type.
- 3Adjust the numbers to model different scenarios.
Frequently asked questions
How many BTU do I need?
A rough rule is 20 BTU per square foot for cooling. Ceiling height, sun, and insulation adjust it up or down.
What happens if the AC is too big?
An oversized unit short-cycles, cooling fast but not removing humidity, which wastes energy and feels clammy.