BTU
Calculator

Calculate BTU requirements for heating and cooling based on room size, insulation, climate, and occupancy.

Room Dimensions

Environment

Insulation
Sun Exposure
Climate

Results

Cooling Required

4,200 BTU

Cooling
Heating Required
4,600 BTU
AC Unit Size
0.5 tons
Est. Monthly Cost
$10.08
Room Area
168 sq ft
Room Volume
1,344 cu ft

Insulation Factor Reference

QualityCoolingHeating
Poor1.3x1.4x
Average1x1x
Good0.85x0.85x
Excellent0.75x0.75x

Learn more

Why is an oversized AC unit wasteful, and how do you calculate the right BTU capacity?

Was this useful?

Frequently Asked Questions

A British Thermal Unit (BTU) is the amount of heat needed to raise the temperature of one pound of water by one degree Fahrenheit. It is the standard unit for measuring heating and cooling capacity.

A general rule is 20 BTUs per square foot of living space. A 500 square foot room needs approximately 10,000 BTUs. Climate, insulation, and ceiling height affect the actual requirement.

One BTU per hour equals approximately 0.293 watts. To convert BTUs to watts, multiply by 0.293. Air conditioners are rated in BTUs while electric heaters often use watts.

BTU Calculator - Heating & Cooling Size Estimator | ToolsCanvas