Electricity Cost Calculator

A kilowatt-hour is the energy used by a 1000-watt device running for one hour. It is the unit electricity is billed in, so multiplying kWh by your price per kWh gives the cost.

Look on the rating label (often on the back or base), in the manual, or on the power supply. It is shown in watts (W) or kilowatts (kW). If only volts and amps are given, multiply them to get watts.

Use the energy price from your own electricity bill or your supplier’s tariff, in your local currency. The result comes out in that same currency. If your tariff has day and night rates, run the calculation twice.

Bills usually add a fixed standing charge, taxes and sometimes higher rates above a monthly threshold. This tool covers only the energy cost of the device itself, which is the part you can change by using it less.

Divide watts by 1000. A 2500 W heater is 2.5 kW. You can also just enter the value in watts and switch the unit toggle to W — the tool does the conversion.

A fridge or freezer cycles on and off, so use its average power over the full day and enter 24 hours, or use the annual kWh figure from its energy label divided by 365 to back out an average.

Not on its own — cost depends on wattage and time together. A 2000 W kettle used for 5 minutes costs far less than a 40 W router left on all day. Both power and hours matter.

They are simple, consistent averages for steady use. Your actual bill counts the real days in the period, so treat the monthly and yearly numbers as close estimates, not exact charges.

Yes. Run each one with its own wattage and typical hours at the same price per kWh, and compare the yearly cost — that is the clearest way to see which is cheaper to own over time.

Only if you account for it. Many devices draw a few watts on standby around the clock; to include that, add a second run with the standby wattage over 24 hours.