AC size for a 500 sq ft room
10,000 BTU
for a 500 sq ft room (0.8 tons) · about 833 W at EER 12
Adjust for the room
| Condition | BTU/h |
|---|---|
| Normal room | 10,000 |
| Very sunny (+10%) | 11,000 |
| Shaded (−10%) | 9,000 |
| Kitchen (+4,000) | 14,000 |
| 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 | 100 kWh | $17 |
| 8 h/day | 200 kWh | $34 |
| 12 h/day | 300 kWh | $51 |
FAQ
What size AC for 500 square feet?
About 10,000 BTU (0.8 tons); add 10% for a sunny room and 4,000 BTU for a kitchen.
How much does it cost to run a 10,000 BTU AC?
At roughly 833 W, 8 hours a day for a month uses 200 kWh, about $34 at $0.17/kWh.