What if my climate is much hotter or colder than average?

Select the climate zone or region that most closely matches yours, hotter climates need a higher BTU-per-sqft factor, as the calculator applies a different multiplier per climate zone before adding occupant and sun-exposure adjustments.

Why does more occupants increase the BTU requirement?

Each person generates body heat, roughly 400-600 BTU/hr, that the AC unit has to remove in addition to the heat gain from the building envelope, so occupancy is added as an extra load on top of the base area-driven estimate.

HVAC / BTU Calculator

Calculate the AC/HVAC size needed for a room based on area and climate.

How this is calculated

BTU = area × climate factor, + occupant and sun-exposure adjustments

Assumptions used in this calculation

Rule of thumb: Uses standard BTU-per-square-foot sizing guidelines, not a full Manual J load calculation.

About this calculator

Estimates the BTU (British Thermal Unit) cooling capacity needed for a room based on floor area, climate zone, occupancy, and sun exposure.

Worked example

300 sqft, moderate climate, 2 occupants

Result: 7,500 BTU needed

Was this helpful?

Frequently asked questions

Electrical Load Calculator

Calculate current draw and recommended breaker size from connected electrical load.

HVAC / BTU Calculator

About this calculator

Frequently asked questions

What if my climate is much hotter or colder than average?

Why does more occupants increase the BTU requirement?

Related calculators