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opnspaces's avatar
opnspaces
Navigator III
Dec 04, 2013

how do I figure the cost of watts?

Can you help me figure this out. I know it should be fairly simple but I just don't seem to get it.

Lets say I have a Kill A Watt. I plug something into that Kill A Watt and it reads 55 watts. How do I use this 55 watts to figure out how much it costs me to run this load 24 hours a day for 30 days? So here's my figures.

55 watt load.
24 hours a day for 30 days.
electricity costs 20 cents a kilowatt.

Do I take 30 * 24 to get 720 hours?
Then divide 720 / 55 to get 13.09 kilowatts?
Then multiply 13.09 Kilowatts by .20 to get 2.61 or $2.61 for 30 days?

Thanks

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  • naturist's avatar
    naturist
    Nomad II
    Dec 04, 2013
    No.

    You do not get charged for kilowatts, you get charged for kilowatt hours. If you burn a 55 watt device for 24 hours every day for 30 days, that is 55 x 24 x 30 = 39,600 watt hours = 39.6 kilowatt hours. 39.6 kilowatt hours x 20 cents = $7.92

    Instead of dividing hours by watts, you multiply hours times watts and divide by 1000 to convert to kilowatt hours from watt hours.

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