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Published on 12.30.05 by Brent Trahan

How Much Electricity Does My Computer Use

Learn how to figure out how much electricity your computer uses.

In this post I’ll explain in detail how much electricity an average computer uses and how much money you’re spending to use your computer.

A typical desktop computer (not including the monitor) uses about 65 watts give or take a few watts depending on the computer. A typical desktop computer with a processor running at a 100% load uses about 90 watts. The typical desktop in hibernation uses about 3-35 watts depending on the hardware.

A typical CRT (the big computer monitor) takes about 80 watts give or take a few. A typical LCD (small flat cool looking monitors) uses about 35 watts give or take a few.

If you want to measure exactly how many watts your computer is using, consider purchasing a kilowatt meter. They are only about $20 and can save you a lot of money.

Click here for my source to the above figures.

The formula to figure out much you’re spending each year on using your computer goes like this: A watts / 1,000 = B kilowatts * C hours per day of usage = D kWh * $0.13 (rate you pay from electricity company per kWh) = E (cost per day) * 365 = F (cost per year).

Click here for my source to the above formula.

I’ll do one for you.

I’m going to figure out how much it cost to run a computer that’s always at full load with the monitor off most of the time. I figure this computer uses about 100 watts 24 hours a day 7 days a week 365 days a year.

100 watts / 1,000 = .1 * 24 (hours per day) = 2.4 * .13 (cost per kWh) = $.31 (per day) * 365 = $112.32 (per year)

With all of this in mind here are a few quick figures:

Please note that these figures are done with the cost per kWh of $.13 This is as close to the average as I can get. Check your electric bill to see how much your being charged to get a better idea of what your computer is costing you to run.

Typical PC at a business:

Computer running 8 hours per day with 17″ CRT on for 8 hours per day = $56.94 per year.
Computer running 8 hours per day with 17″ LCD on for 8 hours per day = $39.86 per year.

*Computer running 24 hours per day with 17″ CRT on for 8 hours per day = $110.08 per year.
*Computer running 24 hours per day with 17″ LCD on for 8 hours per day = $93 per year.

*The computers above that run for 24 hours are set to not sleep when they are not in use.

Typical PC at home:

Computer running 4 hours per day with 17″ CRT on for 4 hours = $ 28.47 per year.
Computer running 4 hours per day with 17″ LCD on for 4 hours = $ 19.93 per year.

*Computer running 24 hours per day with 17″ CRT on for 4 hours per day = $ 94.90 per year.
*Computer running 24 hours per day with 17″ LCD on for 4 hours per day = $ 86.36 per year.

*The computers above that run for 24 hours are set to not sleep when they are not in use.
The figures shown above were calculated with a computer that uses 70 watts, CRT that uses 80 watts, a LCD that uses 35 watts, and an electric company that charges $.13 kWh which is as close as I can come to the national average. Check your bill to see what your being charged. A slight change in this number makes a big difference in the final numbers.

If you want to measure exactly how many watts your computer is using, consider purchasing a kilowatt meter. They are only about $20 and can save you a lot of money.

Click here to see my guide on how you can set your computer to use less electricity.

Still need help? Ask your computer question now.

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9 Responses to “How Much Electricity Does My Computer Use”

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  1. Charles says:

    Thanks for the info Brent. This site is cool.

  2. Cal Tee says:

    Brent, I just added your website to my favorites which says something about it. Thank you so much for the information you got here. It helped me!

  3. manny says:

    great site thanks a million

  4. Jax says:

    The typical home pc now days uses more than 90 watts at full speed.

    My Pc uses 135Watts at full speed

    1.2Ghz CPU
    512MB Ram
    256MB Gefrorce 6200 Graphics
    40GB Hard Drive.

    When you consider most newer Pc have graohics cards that makes the power usage gp Up…

  5. toni says:

    so, how does one convert KWh to barrels of oil?

  6. sara says:

    I was wondering if anyone could help me determine how much 2 additional GB of RAM would cost me in electricity that maybe added to a server.

    Any suggestions or estimates would be greatly appreciated.

  7. Ryan says:

    Thanks! Now I know.

  8. Dorjee says:

    Thank you, this was very helpful to know.

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