Cooling · Room sizing
What size AC for a 150 sq ft room?
A 150 sq ft room with 8 ft ceilings needs about 16,990 BTU/h (1.4 tons) of cooling in a hot climate — buy a 18,000 BTU unit, or 24,000 BTU if the room gets direct sun.
By ceiling height
| Ceiling | BTU/h (shaded) | BTU/h (sunny) | Tons |
|---|---|---|---|
| 8 ft | 16,990 | 20,388 | 1.4 |
| 9 ft | 19,114 | 22,937 | 1.6 |
| 10 ft | 21,238 | 25,485 | 1.8 |
Hot-climate volumetric method (500–600 BTU/h per m³) — the same formula as our BTU calculator, where you can enter exact dimensions. In mild climates use the room-size chart's 20–25 BTU/sq ft column instead.
FAQ
- How many BTU for 150 sq ft?
- In a hot climate with 8 ft ceilings: about 16,990 BTU/h shaded, or 20,388 BTU/h with direct sun. In a mild climate the 20–25 BTU/sq ft rule gives 3,000–3,750 BTU/h — use that as the floor for insulated rooms.
- How many tons is that?
- 16,990 BTU/h equals 1.4 tons of cooling (1 ton = 12,000 BTU/h) — about 5 kW.