How Much Electricity Does a Computer Use?

A computer draws about 200 watts, or 0.20 kWh per hour. Enter your hours and electricity rate below for the exact cost per day, month and year.

–kWh per day
–
kWh / month
–
Cost / day
–
Cost / month
–
Cost / year

Wattage is pre-filled with a typical value for a computer; change any field for your own device, usage and rate. Cost uses your rate × kWh — a US-average placeholder rate of $0.17/kWh is shown; enter your own from your bill for an accurate figure.

A computer in watts and kWh

A computer draws about 200 watts while running. Energy is billed in kilowatt-hours (kWh), and one kWh is 1000 watts for one hour — so a computer uses 200 ÷ 1000 = 0.20 kWh for every hour it is on. Multiply that by the hours you use it and by your rate per kWh to get the cost. The calculator above does it live; change the wattage if your model differs. Kept up every day of the year at 8 hours a day, that is about 584 kWh — roughly $99.28 at the $0.17/kWh placeholder rate used here.

That is a typical desktop with monitor; laptops use far less (30–70 W).

Wattage moves with size, age and model, so treat 200 W as a mid-range starting point rather than a fixed number — the rating plate on your own appliance, or its ENERGY STAR listing, gives the figure to type in. The rate matters just as much: the US Energy Information Administration publishes current average residential prices by state, and the figure on your own bill is better still. This LK Forge calculator recomputes every result as you type.

How to cut what it costs

Two levers change the bill: hours of use and your rate per kWh. Running high-wattage devices less, or shifting them to off-peak hours on a time-of-use plan, has the biggest effect. For a whole-home estimate or to compare devices, use the full electricity bill & appliance calculator.

Other appliances

TV Space Heater Fridge Ceiling Fan Dishwasher Dryer Washing Machine Water Heater Oven Gaming PC Air Conditioner Microwave Hair Dryer Freezer Electricity calculator

Frequently Asked Questions

How much electricity does a computer use?
A computer uses about 200 watts, or 0.20 kWh for every hour it runs. At 8 hours a day that is about 1.60 kWh per day; multiply by your rate per kWh for the cost. Over a 30-day month that is about 48 kWh. Desktops idle far below their peak, so if most of your eight hours is browsing rather than rendering or compiling, lower the wattage field instead of the hours.
How much does it cost to run a computer?
The cost of running a computer is the kWh it uses × your rate per kWh. At a US-average $0.17/kWh and 8 hours a day, a computer costs about $0.27 a day and $8.16 a month. Enter your own rate above for an exact figure.
How is this calculated?
Electricity use for a computer is calculated from watts: energy in kWh equals watts divided by 1000, multiplied by the hours of use. Cost is that kWh figure multiplied by your electricity rate. Your rate per kWh is on your utility bill.
How much does a computer cost to run per year?
Running a computer for 8 hours a day, every day, uses about 584 kWh a year. At the US-average placeholder rate of $0.17/kWh that is roughly $99.28 a year. Change the hours or the rate above and the yearly figure updates with them.