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How much does it cost to run a desktop computer?

Typical wattage
120 W
Cost per hour
$0.02
at 18.16¢/kWh (US avg)
Energy per hour
0.12 kWh

A desktop computer typically draws 120 W. At the US average residential rate of 18.16¢ per kWh (12-month average to August 2026), that is about $0.02 for every hour it runs at full power.

Source lists 120 W awake / 30 W or less asleep for the computer; a monitor adds up to 150 W awake / 30 W or less asleep.

Cost per day and per month

Use per daykWh per dayCost per dayCost per month
1 hour0.12$0.02$0.66
2 hours0.24$0.04$1.33
4 hours0.48$0.09$2.65
8 hours0.96$0.17$5.30

Scenarios show full-power hours. Appliances with thermostats or cycling compressors draw full power for only part of the time they are switched on.

Cost per hour by state

StateRate (12-mo)Cost per hour
Alabama16.44¢$0.02
Alaska26.94¢$0.03
Arizona15.39¢$0.02
Arkansas13.57¢$0.02
California32.34¢$0.04
Colorado17.17¢$0.02
Connecticut27.42¢$0.03
Delaware17.98¢$0.02
District of Columbia24.48¢$0.03
Florida15.41¢$0.02
Georgia15.17¢$0.02
Hawaii44.27¢$0.05
Idaho12.77¢$0.02
Illinois18.91¢$0.02
Indiana16.90¢$0.02
Iowa14.20¢$0.02
Kansas15.13¢$0.02
Kentucky13.94¢$0.02
Louisiana13.02¢$0.02
Maine29.60¢$0.04
Maryland21.18¢$0.03
Massachusetts30.39¢$0.04
Michigan21.28¢$0.03
Minnesota16.28¢$0.02
Mississippi14.85¢$0.02
Missouri13.97¢$0.02
Montana13.94¢$0.02
Nebraska12.74¢$0.02
Nevada13.45¢$0.02
New Hampshire26.95¢$0.03
New Jersey23.74¢$0.03
New Mexico16.51¢$0.02
New York28.60¢$0.03
North Carolina14.79¢$0.02
North Dakota12.35¢$0.01
Ohio18.41¢$0.02
Oklahoma13.81¢$0.02
Oregon15.53¢$0.02
Pennsylvania20.86¢$0.03
Rhode Island29.44¢$0.04
South Carolina15.77¢$0.02
South Dakota14.28¢$0.02
Tennessee13.61¢$0.02
Texas15.98¢$0.02
Utah13.26¢$0.02
Vermont23.90¢$0.03
Virginia16.64¢$0.02
Washington14.20¢$0.02
West Virginia15.53¢$0.02
Wisconsin18.79¢$0.02
Wyoming14.01¢$0.02

Calculate with your own numbers

Frequently asked questions

How many watts does a desktop computer use?

A typical desktop computer uses 120 W, according to Virginia Cooperative Extension. Check the label on your model.

How much does it cost to run a desktop computer per hour?

About $0.02 per hour at full power, at the US average rate of 18.16¢ per kWh.

How much does it cost to run a desktop computer for a month?

Running it 1 hour a day at full power costs about $0.66 a month at the US average rate. Your cost depends on your hours and your state's rate.

How many kWh does a desktop computer use?

About 0.12 kWh per hour at full power (watts ÷ 1,000).

How can I find my desktop computer's exact wattage?

Check the rating label or manual, or measure it with a plug-in electricity usage meter, which shows real watts and kWh.

Rates: EIA, 12-month residential average. Cost = watts × hours ÷ 1,000 × rate (US Department of Energy method).

Sources

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