Look on the box. It should say somewhere how many amps it uses, or is rated at. That tells you that it is using X amount of amps every hour. Say that it uses 5 amps and it plugs into a standard 120 volt plug, your using 600 watts an hour. 600watts per hour equals .6kWh (or kilowatt hours) and that is what the electric company charges you for. So if your paying 10 cents per kilowatt hour your paying $1.44 per day to run it. I hope this helps. I'm pretty sure my math is right.