A 18,000 BTU air conditioner cools about 700 up to 1,000 sq ft, per ENERGY STAR's sizing chart (8-foot ceilings). It draws roughly 1,250–1,682 W, about 10.4–14 amps at 120 V.
- Room size
- 700–1,000 sq ftENERGY STAR chart
- Power
- 1,250–1,682 WEfficient to older
- Per hour
- 21¢–28¢At 16.48¢/kWh
Power, amps and cost
| Efficient (ENERGY STAR) | Older (2014 minimum) | |
|---|---|---|
| Watts | 1,250 W | 1,682 W |
| Amps at 120 V | 10.4 A | 14 A |
| Cost per hour | 21¢ | 28¢ |
Watts ≈ BTU ÷ CEER (combined energy efficiency ratio). CEER includes standby power, so running watts are approximate; check the unit's label.
Sizing chart
| Area to cool | Capacity needed |
|---|---|
| 100 to 150 sq ft | 5,000 BTU/hr |
| 150 to 250 sq ft | 6,000 BTU/hr |
| 250 to 300 sq ft | 7,000 BTU/hr |
| 300 to 350 sq ft | 8,000 BTU/hr |
| 350 to 400 sq ft | 9,000 BTU/hr |
| 400 to 450 sq ft | 10,000 BTU/hr |
| 450 to 550 sq ft | 12,000 BTU/hr |
| 550 to 700 sq ft | 14,000 BTU/hr |
| 700 to 1,000 sq ft | 18,000 BTU/hr |
| 1,000 to 1,200 sq ft | 21,000 BTU/hr |
| 1,200 to 1,400 sq ft | 23,000 BTU/hr |
| 1,400 to 1,500 sq ft | 24,000 BTU/hr |
| 1,500 to 2,000 sq ft | 30,000 BTU/hr |
| 2,000 to 2,500 sq ft | 34,000 BTU/hr |
ENERGY STAR chart, assuming 8-foot ceilings. Heavily shaded: −10%. Very sunny: +10%. More than two people: +600 BTU each. Kitchen: +4,000 BTU.
Questions people ask
How many square feet does a 18,000 BTU air conditioner cool?
A 18,000 BTU air conditioner cools about 700 up to 1,000 sq ft , per ENERGY STAR's sizing chart (8-foot ceilings).
How many watts does a 18,000 BTU air conditioner use?
About 1,250 W for an efficient model to 1,682 W for an older one (BTU ÷ CEER).
How much does it cost to run a 18,000 BTU air conditioner?
About 21¢–28¢ per hour of compressor run time at the US average 16.48¢/kWh; 8 hours a day for a month is roughly $50.10–$67.42.
Does a 18,000 BTU air conditioner need a 240 V outlet?
Check the nameplate. Many large window units run on 120 V, but some of the largest need a 240 V outlet or a dedicated circuit. Use the plug type and circuit the manufacturer specifies.