PlugFacts

Checked against official sources on 15 October 2026

Maintained by Karan S.

How much does a window air conditioner cost to run?

About $8.59 a month

for a typical 8,000–12,000 BTU room air conditioner in , at 18.31 cents per kWh.

Uses
1.54 kWh a day
Draws while running
900–1,200 W
Needs at start-up
about 2,400 W

Air conditioning is where summer bills come from. A window or room unit in the 8,000–12,000 BTU range is rated at about 563 kWh a year, but a hot, humid summer or long days at home can push that much higher. Getting the size right for the room matters more than almost anything else.

Work out your own air conditioner

Typical use: 563 kWh a year

cents per kWh

Per day$0.28
Per month$8.59
Per year$103

Bigger units use more

Yearly figures are ENERGY STAR's rated use for room air conditioners. Hot climates and long hours push real use higher. Costs below use the price you set above.

Cooling capacity Energy per year Cost per year
Up to 8,000 BTU168 models 400 kWh $73
8,001 to 12,000 BTU269 models 563 kWh $103
12,001 to 18,000 BTU96 models 728 kWh $133
Over 18,000 BTU42 models 1,353 kWh $248

What it costs in other countries

For a typical 8,000–12,000 BTU room air conditioner, at each country's official average electricity price.

CountryPrice per kWhPer monthPer year
United States18.31 cents$8.59$103
United Kingdom26.32 pence£12£148
Germany36.18 cents€17€204
Ireland38.71 cents€18€218
France24.85 cents€12€140
Spain25.09 cents€12€141
Italy31.42 cents€15€177
Netherlands24.40 cents€11€137

Prices from the U.S. EIA, Ofgem and Eurostat; see Sources below. To see another country, pick it at the top of the page; we cover 51.

How to cut the cost of running your air conditioner

  1. Use a ceiling fan on milder days

    A 10,000 BTU window unit draws at least 900 W while running, against about 30 W for a typical ceiling fan on high.

    Saves at least $0.16 for every hour

  2. Get the size right for the room

    In the ENERGY STAR data, a typical 8,001–12,000 BTU unit uses 165 kWh a year less than a 12,001–18,000 BTU one. Bigger isn't better if the room doesn't need it.

    Saves about $30 a year

  3. Set the thermostat a little warmer

    Each degree cooler keeps the compressor running longer.

  4. Seal the gaps around the unit

    Gaps and open doors let cool air out and warm air in.

Savings use the electricity price you set above and figures from this page's sources.

What can power it

To run a 10,000 BTU window air conditioner from a generator or a portable power station, check two numbers. It must supply the running power, about 900–1,200 W, all the time. It must also handle about 2,400 W for a moment each time it starts.

Check a specific setup with the generator size calculator.

Common questions

How many watts does a window AC use?

Champion's generator wattage chart lists a 10,000 BTU window air conditioner at 900–1,200 W while running and 1,800–2,400 W for a moment when the compressor starts. A 5,000 BTU unit is listed at 450–600 W running.

How much electricity does a room AC use per year?

ENERGY STAR rates a typical 8,000–12,000 BTU unit at about 563 kWh a year, across 269 models. Your use depends heavily on climate and hours.

How much does it cost to run an air conditioner per day?

About $0.28 a day in the United States, at the average price of 18.31 cents per kWh, or about £0.41 a day in the UK at 26.32 pence, for a typical 8,000–12,000 BTU room air conditioner. That adds up to about $103 or £148 a year.

Related

Sources

Last checked 15 October 2026. How we get our numbers.