See how much electricity an appliance uses and what it costs. Enter its watts, how long you run it each day and your price per unit. You get the energy in kWh and the cost per day, month and year.
Use the watts printed on the appliance label. For appliances that cycle on and off, such as a fridge or AC, use the average running hours. Your bill may also include fixed charges and taxes.
Formulas and assumptions
- Energy per day (kWh): watts times number of appliances times hours, divided by 1000
- Energy per month: energy per day times days of use
- Cost: energy in kWh times your price per unit
- Watts from amps: single phase watts = volts times amps times power factor
Example
A 1500 W air conditioner run 8 hours a day uses 12 kWh per day, or 360 kWh over 30 days. At a price of 40 per unit that costs 480 per day and 14,400 per month.
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply its power in watts by the hours used, divide by 1000 to get kWh, then multiply by your price per unit.
Where do I find the wattage of an appliance?
Look at the label or nameplate on the back or bottom, or in the manual. If only amps are shown, multiply by the voltage.
Why is my bill higher than the calculator says?
Bills often include fixed charges, fuel or tax adjustments and tiered rates where higher usage costs more per unit. Appliances that cycle on and off also use less than their rated watts.
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