AC BTU calculator

Region and unitsSwitching region converts your dimensions; the charts are the same. Your numbers stay in this browser only.

Room length (ft)ftStarting value: BTUtally starting example, read 2026-09-20; edit it.Room width (ft)ftFloor area: 180 sq ft.

Ceiling height (ft)ftStarting value: ENERGY STAR, Room Air Conditioners, cooling capacity chart, read 2026-09-20; edit it.People regularly in the roomStarting value: ENERGY STAR, Room Air Conditioners, sizing chart notes, read 2026-09-20; edit it.

Sun exposureThe room is a kitchenAdds 4,000 BTU/h (ENERGY STAR, Room Air Conditioners, sizing chart notes).

Result

Cooling needed: 6,000 BTU/h
Room unit class: 6,000 BTU room unit
Tons: 0.50 tons
Kilowatts: 1.76 kW
Chart band: 150-250 sq ft: 6,000 BTU/h
Adjustments: none

180 sq ft (16.7 m²) falls in the chart band 150-250 sq ft (ENERGY STAR, Room Air Conditioners, cooling capacity chart). Sizing estimates from published charts and rules of thumb, each listed with its source and the day it was read: an installer's load calculation (Manual J for a US home, a room-by-room heat loss calculation in the UK) is the final word.

Free calculator by BTUtally. Open the full version for the room list, the guide and the sources. Sizing estimates, not an installer's calculation.