Before we can understand how much electricity costs, we have to know how it’s measured.
What exactly is a kilowatt hour?
When you buy gas they charge you by the gallon. When you buy electricity they charge you by the kilowatt-hour (kWh). When you use 1000 watts for 1 hour, that’s a kilowatt-hour.
To get kilowatt-hours, take the wattage of the device, multiply by the number of hours you use it, and divide by 1000. (Dividing by 1000 changes it from watt-hours to kilowatt-hours.)
Here’s the formula to figure the cost of running a device:
wattage x hours used ÷ 1000 x price per kWh = cost of electricity
For example, let’s say you leave a 100-watt bulb running continuously (730 hours a month), and you’re paying 15¢/kWh. Your cost to run the bulb all month is 100 x 730 ÷ 1000 x 15¢ = $10.95.
If your device doesn’t list wattage, but it does list amps, then just multiply the amps times the voltage to get the watts. For example: [read more]