Work out how much an appliance costs to run per day, month and year from its watts, hours of use and your price per kWh.
Cost a month
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| Period | Energy | Cost |
|---|
Energy (kWh) = power (W) × hours ÷ 1,000
Cost = energy (kWh) × price per kWh
A 1,500 W heater used 3 hours a day uses 1,500 × 3 ÷ 1,000 = 4.5 kWh a day. At 0.20 per kWh that’s 0.90 a day, or about 27 a month.
Look for a label on the back or bottom, or in the manual. It shows watts (W) or kilowatts (kW). If it only shows amps, multiply amps by your mains voltage (230 V in most of the world, 120 V in North America) to get watts.
On your electricity bill, as the unit rate or energy charge per kilowatt hour. If you have different day and night rates, use the rate for when you run the appliance.
Fridges, air conditioners and heaters switch on and off to hold a temperature, so they don't use full power all day. For those, use the average power from the energy label, or fewer hours a day.
Any. Enter your price per kWh in your own currency, and the costs come out in the same currency.
