AC size for a 350 sq ft room
7,000 BTU
for a 350 sq ft room (0.6 tons) · about 583 W at EER 12
Adjust for the room
| Condition | BTU/h |
|---|---|
| Normal room | 7,000 |
| Very sunny (+10%) | 7,700 |
| Shaded (−10%) | 6,300 |
| Kitchen (+4,000) | 11,000 |
| Each extra person over 2 (+600) | +600 |
Rule of thumb: 20 BTU per sq ft with 8 ft ceilings (ENERGY STAR sizing guidance).
Monthly running cost at $0.17/kWh
| Use | Energy | Cost |
|---|---|---|
| 4 h/day | 70 kWh | $12 |
| 8 h/day | 140 kWh | $24 |
| 12 h/day | 210 kWh | $36 |
FAQ
What size AC for 350 square feet?
About 7,000 BTU (0.6 tons); add 10% for a sunny room and 4,000 BTU for a kitchen.
How much does it cost to run a 7,000 BTU AC?
At roughly 583 W, 8 hours a day for a month uses 140 kWh, about $24 at $0.17/kWh.