What Size AC for 350 Sq Ft?
A 350 sq ft space needs about 7,000 BTU/h of cooling (0.58 tons), so the nearest size is 8,000 BTU. This assumes an 8 ft ceiling and average sun. It is a rule of thumb (20 BTU per sq ft), not an engineered load.
AC size for 350 sq ft by situation
| Scenario | BTU/h | Tons | Suggested size |
|---|---|---|---|
| Heavily shaded (−10%) | 6,300 | 0.53 | 8,000 BTU |
| Average sun, 8 ft ceiling | 7,000 | 0.58 | 8,000 BTU |
| Very sunny (+10%) | 7,700 | 0.64 | 8,000 BTU |
| Kitchen (+4,000 BTU) | 11,000 | 0.92 | 12,000 BTU |
| 9 ft ceilings (+12.5%) | 7,875 | 0.66 | 8,000 BTU |
| 10 ft ceilings (+25%) | 8,750 | 0.73 | 10,000 BTU |
| Hot climate (+10%) | 7,700 | 0.64 | 8,000 BTU |
Rule-of-thumb figures for a two-person space; each extra person over 2 adds about 600 BTU.
How it is calculated
350 sq ft × 20 BTU × (8 ÷ 8) = 7,000 BTU/h
7,000 ÷ 12,000 = 0.58 tons
Sunny: 7,000 × 1.1 = 7,700 · Kitchen: 7,000 + 4,000 = 11,000
Which type of AC for 350 sq ft?
- Window unit – The usual choice at this size is a 8,000 BTU window unit. Units above roughly 15,000 BTU often need a 230V circuit, but this size normally stays on 115V.
- Portable unit – Portable units lose capacity to exhaust-hose heat. Expect to need about 9,100 BTU nominal (≈30% more) to match a window unit here.
- Mini-split – A 8,000 BTU single-zone mini-split is the quiet, efficient alternative and also heats, with no window blocked.
Frequently asked questions
How many BTU do I need for 350 square feet?
About 7,000 BTU/h for an 8 ft ceiling in average conditions (350 × 20). That is 0.58 tons, so the closest unit is 8,000 BTU.
Is 8,000 BTU enough for 350 sq ft if the room is sunny?
A very sunny space needs about 7,700 BTU, so 8,000 BTU is recommended – the same size as the average case.
What if the 350 sq ft space has 10 ft ceilings?
The load rises 25% to 8,750 BTU, so choose 10,000 BTU instead of 8,000 BTU. Volume matters, not just floor area.