# BTU Calculator

> BTU calculator: size heating and cooling by room dimensions, insulation, and climate to get the right BTU output. Free, runs locally, no signup required.

- **Canonical URL:** https://boringtoolskit.com/btu-calculator/
- **Category:** Everyday Calculators
- **Evidence level:** authored-methodology
- **Reviewed:** August 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Base load is about 18-20 BTU/hr per square foot of floor area, adjusted upward for occupants (about +600 each) and climate.

## Worked example

A 15 x 12 ft room (180 sq ft) with 2 occupants needs about 3,160 BTU/hr of heating or cooling capacity.

## Sources

- [Calculation methodology and verification standard](/methodology/)

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