Work out what an appliance costs to run per day, month and year.
Calculated locally in your browser.
How is electricity cost calculated?
Energy (kWh) = watts ÷ 1000 × hours, and cost = energy × price per kWh (found on your electricity bill). For example, a 1,500 W heater used 3 hours a day at 0.17 per kWh costs about 0.77 per day and 23 per month. Running longer or at higher wattage costs more.
Understanding your result
Watts measure power; kilowatt-hours measure energy used over time. Running longer or at higher wattage costs more.
Formula and method
Energy (kWh) = watts ÷ 1000 × hours. Cost = energy × price per kWh. Find your price per kWh on your electricity bill.
Assumptions and limitations
The figure is an estimate from the wattage, hours and price you enter. Real bills vary with tariffs, standing charges, appliances that cycle on and off, and devices whose draw changes with use. It cannot read your meter or account for taxes, so treat the result as a guide rather than an exact charge.
Worked example
A 1,500 W heater used 3 hours a day at 0.17 per kWh costs about 0.77 per day and 23 per month.
How to use this tool
- Enter the appliance power in watts.
- Enter the hours used per day and your price per kWh.
- Press Calculate.
About the Electricity Cost Calculator
The Electricity Cost Calculator estimates how much an appliance costs to run, turning its wattage and usage into a daily, monthly and yearly bill.
Who should use this tool
Households watching their energy bills, renters comparing appliances, and anyone curious what a heater, kettle or old fridge really costs to run. Useful when deciding whether to replace a power-hungry device or cut back on how long it runs.
Benefits
- Turns wattage and hours into daily, monthly and yearly costs
- Helps compare the running cost of different appliances
- Shows the saving from cutting back usage time
- Works in your browser with no account needed
Practical use cases
- Estimating what a space heater adds to a bill
- Comparing an old appliance against a newer model
- Deciding whether long device runtimes are worth it
- Budgeting the yearly cost of an always-on device
Explore all Productivity tools
Frequently asked questions
Where do I find my price per kWh?
It’s listed on your electricity bill as the unit rate or price per kWh. Enter that figure for an accurate estimate.
How do I find an appliance's wattage?
Check the label or rating plate, often on the back or base of the device, or look in its manual. Values are usually shown in watts (W) or sometimes amps and volts, which multiply to give watts. For devices that vary, use the typical running wattage rather than the peak.
Why is my real bill higher than the estimate?
Bills include more than one appliance's energy. A standing charge, taxes, other devices, and appliances that cycle or sit on standby all add up. The calculator isolates a single device at the price and hours you enter, so it is a component of the bill, not the whole total.