🏠 Interior · Free

What size AC
does the room need?

Enter the room size and a few details to get the cooling power — in BTU and kW — for the right air conditioner.

▶︎ How to use — watch it work on real numbers

Free air conditioner size (BTU) calculator

Picking the right air conditioner size matters: too small and it never cools; too big and it short-cycles, wasting energy and leaving the room humid. This BTU calculator starts from your floor area (about 300–340 BTU per m²), then adjusts for ceiling height, sun exposure, the number of people (each adds heat) and hot spots like a kitchen. The result is a recommended cooling power in both BTU/h and kW.

Reading the result

Match the recommended BTU to a unit's rating — it's fine to round up to the nearest common size (9,000 / 12,000 / 18,000 / 24,000 BTU). Good insulation and shading let you size down; large windows and top-floor rooms push you up. Remember 1 kW ≈ 3,412 BTU/h.

What size AC do I need?
~300–340 BTU per m², adjusted for ceiling, sun and people. This tool combines them.
BTU to kW?
Divide BTU/h by 3412 to get kW. The tool shows both.

Related: Paint Calculator · Unit Converter