How to use Electricity Cost Calculator
- Enter the power of the appliance (watts or kilowatts). It is usually on the label.
- Enter the hours used per day and your price per kWh from your bill.
- Optional: enter how many identical devices you have.
- Read the cost per day, week, month and year.
About this tool
Energy in kilowatt-hours (kWh) is power in kilowatts multiplied by the hours used: a 1,500 W heater running for 3 hours uses 4.5 kWh. The cost is the energy multiplied by your price per kWh.
Many appliances only draw full power part of the time (fridges, ovens and heaters cycle on and off), so real costs are often lower than the maximum. Standing charges, taxes and tiered tariffs are not included.
Privacy: This tool runs in your browser. What you type or choose is not sent to a server by this website.
Common questions
How do I convert watts to kWh?
Divide the watts by 1,000 to get kilowatts, then multiply by the hours used.
Where do I find my price per kWh?
On your electricity bill or in your supplier’s tariff details. It is often given in pence or cents, so convert it to pounds or dollars (for example 28p = 0.28).