2026-06-01
How many BTU do you need? Portable AC room-size guide
Match BTU to room size so you do not overspend on cooling you cannot use.
As a rule of thumb, aim for roughly 60–80 BTU per square metre for a typical UK room with average insulation.
A 20 m² bedroom usually needs around 7,000–9,000 BTU. Open-plan spaces and sunny rooms need more.
Use our BTU calculator, then compare live Amazon and eBay prices on our best portable AC page.