Cooling · Room sizing
What size AC for a 450 sq ft room?
A 450 sq ft room with 8 ft ceilings needs about 50,970 BTU/h (4.2 tons) of cooling in a hot climate — buy a 60,000 BTU unit, or 60,000 BTU if the room gets direct sun.
By ceiling height
| Ceiling | BTU/h (shaded) | BTU/h (sunny) | Tons |
|---|---|---|---|
| 8 ft | 50,970 | 61,164 | 4.2 |
| 9 ft | 57,342 | 68,810 | 4.8 |
| 10 ft | 63,713 | 76,456 | 5.3 |
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 450 sq ft?
- In a hot climate with 8 ft ceilings: about 50,970 BTU/h shaded, or 61,164 BTU/h with direct sun. In a mild climate the 20–25 BTU/sq ft rule gives 9,000–11,250 BTU/h — use that as the floor for insulated rooms.
- How many tons is that?
- 50,970 BTU/h equals 4.2 tons of cooling (1 ton = 12,000 BTU/h) — about 15 kW.