How much does it cost to run a window AC unit?
A 10,000 BTU window AC drawing about 1,000 W while its compressor runs costs $0.17 an hour at 17¢ per kWh — $1.36 for 8 hours of compressor time.
How to work it out
- 1,000 W ÷ 1,000 = 1 kW × $0.17/kWh = $0.17 an hour
- 1 kW × 8 h = 8 kWh × $0.17 = $1.36 a day
- 8 kWh × 365 days = 2,920 kWh a year = $496.40 ($41.37 a month)
Champion’s generator chart lists a 10,000 BTU window unit at 900–1,200 running watts and a 5,000 BTU unit at 450–600 W. This page uses 1,000 W for the larger size; check the label on yours, which usually lists watts or amps.
Adjust for your project
More options: Days/yr
- Cost per hour
- $0.17
- Cost per month (average)
- $41.37
- Cost per year
- $496.40
- Energy per day
- 8 kWh
- Energy per year
- 2,920 kWh
The same appliance at other hours per day
| Hours used per day | Energy per day | Cost per day | Cost per month (average) |
|---|---|---|---|
| 1 | 1 kWh | $0.17 | $5.17 |
| 2 | 2 kWh | $0.34 | $10.34 |
| 4 | 4 kWh | $0.68 | $20.68 |
| 8 | 8 kWh | $1.36 | $41.37 |
| 12 | 12 kWh | $2.04 | $62.05 |
| 24 | 24 kWh | $4.08 | $124.10 |
What to know about window AC running costs
- Compressor hours, not hours on. Once the room is cool, the compressor cycles off and only the fan runs. Eight hours of compressor time might be a whole hot afternoon and evening.
- A 5,000 BTU unit costs about half. At around 500 W it uses roughly half the energy per hour — fine for a small bedroom, not for a living room.
- Efficiency labels matter. Two units with the same BTU rating can draw quite different watts; the higher the efficiency rating, the lower the watts for the same cooling.
- Starting watts are a generator issue, not a bill issue. The 1,800–2,400 W start surge on Champion’s chart lasts seconds, so it barely shows on the bill — but it decides the generator or inverter size.
In humid summers a dehumidifier often runs alongside — see the cost to run a dehumidifier — and a ceiling fan lets you set the AC a little warmer for pennies: the cost to run a ceiling fan. Running one from a generator or battery instead? What size generator to run a refrigerator shows how starting watts stack, and what size generator for a 30 amp camper handles the RV version of the same air conditioner question.
Different size? Use the full Electricity Cost Calculator.
What you’ll need
- Plug-in electricity usage monitorBudget price
Plugs in between the wall and a 120 V appliance and shows real watts and kWh over a day — the honest way to fill in a load list, especially for fridges that cycle on and off.
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Frequently asked questions
How much does it cost to run a 5,000 BTU window AC?
At about 500 W, $0.09 an hour, or $0.68 for 8 hours of compressor time at 17¢ per kWh.
How much does it cost to run a window AC all summer?
Eight compressor hours a day for 90 days is 720 kWh — about $122.40 for the season at 17¢ per kWh.
Other common sizes
- The cost to run a space heater — $0.26 an hour at 17¢/kWh (1,500 W)
- The cost to run a dehumidifier — $1.60 a day at 17¢/kWh (12 hours)
- The cost to run a ceiling fan — $0.15 a day at 17¢/kWh (12 hours)
Sources
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- Champion Power Equipment — Generator Wattage Chart (opens in a new tab) — Typical running and starting watts for household, RV and job-site appliances (a manufacturer’s planning chart — your nameplate wins).