Calculators & Converters
Electricity cost calculator
Enter the appliance's power, how many hours a day you use it and what you pay per kilowatt-hour. See the energy and cost per day, month and year.
- Free, no sign-up
- Runs in your browser
- Nothing uploaded
Appliance
Only changes the symbol and number format. No exchange rates are used.
Find it on the label. A kettle is about 2,000 W, a laptop 50 W, an air conditioner 1,000 to 3,500 W.
Price
From your bill. One kWh is 1,000 watts for one hour.
Extras (optional)
Your grid's figure, for example 0.2 to 0.8 kg per kWh. Leave at 0 to skip.
Result
Table
How to use this tool
- Enter the appliance's power in watts from its label or manual.
- Enter how many hours a day it runs and, if you have several, how many there are.
- Enter your electricity price per kWh from your bill, with a currency.
- Read the energy and cost per day, week, month and year, plus an optional carbon figure.
How it works
Electricity is billed in kilowatt-hours. One kWh is the energy used by 1,000 watts running for one hour. Multiply the power in kilowatts by the hours of use to get the energy, then multiply by the price per kWh to get the cost.
kWh per day = watts × hours × quantity ÷ 1000
Cost = kWh × price per kWh
Good to know
A 1,500 W heater running three hours a day uses 4.5 kWh. At 0.15 per kWh that is about 0.68 a day, 20 a month and 246 a year. Use the calculator to compare an old and a new appliance, or to see whether leaving something on standby is worth switching off.
The rating on the label is the maximum draw. Fridges, air conditioners and kettles with thermostats cycle on and off, so their real average use is lower. Smart plugs with energy monitoring give the most accurate figure. Some tariffs charge different prices at different times of day, so use the rate that applies when the appliance runs. The currency selector only changes the symbol and number format.
Frequently asked questions
How do I calculate the cost of running an appliance?
Multiply its power in kilowatts by the hours used, then by the price per kWh. The calculator does this for you.
What is a kWh?
A kilowatt-hour is the energy of a 1,000-watt appliance running for one hour. It is the unit on your electricity bill.
Why is my real bill lower than the estimate?
Many appliances do not run at full power all the time. Use a smart plug to measure the real average.
Is anything sent anywhere?
No. The calculation runs in your browser.