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Appliance running cost calculator
Every appliance in a home quietly adds to the electricity bill, and the worst offenders are not always the ones you expect.
Enter the price per kWh in your own currency.
A device that draws a lot of power but runs for minutes, like a kettle, can cost less over a year than a modest one that runs around the clock, like a fridge. This tool puts a real number on a single appliance so you can see which ones matter. Enter the power rating in watts, the hours you run it on an average day, the price you pay per kilowatt-hour, and how many days a year you use it, and it returns the cost per year, per month and per day, along with the energy used in kilowatt-hours. The power rating is the key input. It is printed on a label on the appliance, on the back or underneath, or in the manual, given in watts or sometimes in amps that you multiply by the voltage. A plug-in energy monitor reads it directly and also catches what a device uses on standby. The sum is straightforward once you have the rating: a device drawing 1,000 watts for one hour uses one kilowatt-hour, and the cost is that energy multiplied by your unit price. The trap is the hours. Many appliances do not run at full power for the whole time they are switched on. A fridge compressor, a washing machine heater and an oven element all cycle on and off, so the hours at full draw are far fewer than the time the appliance is plugged in. Estimating the real hours at full power, rather than the time on the clock, is what makes the figure accurate. Use it to compare an old appliance against a new one, to decide whether something is worth leaving on, or to hunt down what is pushing a bill up.
How it works
- Find the power rating in watts on the appliance label, the manual, or a plug-in energy monitor.
- Enter the hours it runs at full power on an average day, not just the hours it is switched on.
- Enter the price you pay per kilowatt-hour, in your own currency.
- Set how many days a year you use it; an everyday item is 365, a seasonal one far fewer.
- The tool turns watts into kilowatts, multiplies by the hours for daily energy, applies the price, and scales it to a day, month and year.
yearly cost = (watts / 1000) x hours per day x price per kWh x days per year
Power in watts is divided by 1,000 to give kilowatts, because energy is measured in kilowatt-hours. Multiplying by the hours of full-power use gives the energy used in a day, and multiplying that by the price per kilowatt-hour gives the daily cost. Scaling by the days used a year gives the annual figure, the monthly cost is the year divided by twelve, and the energy in kilowatt-hours is the same product without the price applied.
- watts
- power rating of the appliance, from its label or a monitor
- hours per day
- time at full power on an average day, not just time switched on
- price per kWh
- what you pay for a unit of electricity
- days per year
- how many days a year you use it
Typical power of common appliances
| Kettle or toaster | about 2,000 to 3,000 W | high power but used for minutes |
| Washing machine or dishwasher | about 2,000 W peak | mostly to heat water, then far less |
| Fridge or freezer | about 100 to 200 W when running | cycles on and off all day |
| LED light bulb | about 5 to 10 W | cheap to leave on by comparison |
Worked example
A 2,000-watt appliance runs for 3 hours a day, every day, with a unit rate of 0.25: it uses 6 kWh a day (2 kW times 3 hours), costing 1.50 a day, which works out at about 45.63 a month and 547.50 a year, using 2,190 kWh. By contrast a 60-watt fridge that effectively runs a quarter of the day, around 6 hours at full draw, uses far less daily energy yet still adds up because it never takes a holiday. Comparing the two shows why running hours matter as much as the wattage on the label.
Key facts
- Running cost is power times hours times price, so hours matter as much as wattage.
- A high-power device used briefly can cost less than a low-power one left on all day.
- Many appliances cycle on and off, so full-power hours are fewer than the time switched on.
- A plug-in energy monitor reads real use, including the standby a label does not show.
Tips
- Count only the hours at full power, not the time the appliance sits switched on.
- Use a plug-in monitor for cycling devices like fridges, where guessing the hours is hard.
- Compare an old and a new appliance by running the tool twice and weighing the saving against the price.
- Tackle the big yearly costs first, which are usually constant-running or heating appliances, not brief high-power ones.
Frequently asked questions
Where is the power rating on an appliance?+
Look for a label on the back, the base or inside a door, or check the manual. It is usually given in watts (W) or kilowatts (kW); 1 kW is 1,000 W. Some labels show amps (A) instead, in which case multiply the amps by the mains voltage to get watts. A plug-in energy monitor is the surest way and shows real use including standby.
Why does the result depend so much on hours?+
Because cost is energy, and energy is power multiplied by time. A high-wattage device used briefly can cost less than a low-wattage one left on all day. Getting the hours right, and counting only the time at full power rather than the time switched on, is what makes the estimate reliable.
My appliance switches on and off. What hours do I enter?+
Enter the equivalent hours at full power, not the time it is plugged in. A fridge runs its compressor perhaps a quarter to a third of the day, so a device on for 24 hours might draw full power for only 6 to 8. An oven that holds heat cycles its element similarly. If unsure, a plug-in monitor measures the real total for you.
Does standby power count?+
It can add up. Many devices draw a small amount when off but still plugged in, often a watt or two, which over a year is small per device but real across a whole house. A plug-in monitor captures it; to include it here, add the standby hours and power as a separate run.
How do I compare an old appliance with a new one?+
Run the tool twice, once with each wattage and the same hours and price, then compare the yearly costs. The gap is the annual saving from switching. Weigh that saving against the price of the new appliance to see how many years it takes to pay back.
Will this match my bill?+
It estimates one appliance, while your bill is the whole home plus the standing charge. Add up several appliances and you approach the energy part of the bill, but real use varies day to day, so expect a close estimate rather than an exact match.
Things to watch
- Entering the time switched on rather than the hours at full power overstates the cost of any cycling appliance.
- This estimates one appliance only; it does not include the standing charge or the rest of the home.
- Real use varies day to day, so treat the yearly figure as an estimate to compare with, not an exact bill.
Last updated: 2026
This is an estimate for general guidance, not financial, tax, legal or medical advice. Figures can change and individual circumstances vary. Always confirm with an official source before making decisions.
Built and maintained by Vikas Dulgunde. Editorial standards.