Room BTU Calculator — Cooling & Heating BTU/h

How to use

1. Measure the room: length × width in feet, or enter the area directly.
2. Set ceiling height, insulation quality and sun exposure honestly.
3. Add the usual head-count and tick the box if it is a kitchen.
4. Read BTU/h, tons and kW — then buy the nearest unit above that number.

About this tool

Buying an air conditioner or heater on a guess is how rooms end up clammy in July and cold in January. This calculator sizes a room the way installers ballpark it: about 20 BTU per square foot for cooling, then adjusted for the things that actually change the load — ceiling height (a 10-foot ceiling moves 25% more air volume), insulation quality, sun exposure, how many people sit in the room and whether cooking appliances share the space. You get cooling BTU/h rounded sensibly, the tonnage equivalent, a kW figure and an honest heating range, plus a note telling you when a window unit stops making sense and a mini-split is the right hardware. Everything computes locally in your browser — no numbers leave the page.

FAQ

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