Cooling · Room sizing
What size AC for a 350 sq ft room?
A 350 sq ft room with 8 ft ceilings needs about 39,644 BTU/h (3.3 tons) of cooling in a hot climate — buy a 48,000 BTU unit, or 48,000 BTU if the room gets direct sun.
By ceiling height
| Ceiling | BTU/h (shaded) | BTU/h (sunny) | Tons |
|---|---|---|---|
| 8 ft | 39,644 | 47,572 | 3.3 |
| 9 ft | 44,599 | 53,519 | 3.7 |
| 10 ft | 49,555 | 59,465 | 4.1 |
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 350 sq ft?
- In a hot climate with 8 ft ceilings: about 39,644 BTU/h shaded, or 47,572 BTU/h with direct sun. In a mild climate the 20–25 BTU/sq ft rule gives 7,000–8,750 BTU/h — use that as the floor for insulated rooms.
- How many tons is that?
- 39,644 BTU/h equals 3.3 tons of cooling (1 ton = 12,000 BTU/h) — about 11.6 kW.