Electricity cost calculator
Enter the power of an appliance, the hours per day and your price per kWh, and see the energy used in kWh and what it costs per day, month and year.
In watts; 2 kW works too. It is on the rating plate or in the manual.
How long the appliance is on per day, on average.
It is on your energy bill, including tax.
Fill in the fields; the answer appears here straight away.
How it's worked out
How it works
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Enter the values
Type the numbers or the formula. Decimals may use a point or a comma. No idea? Click Fill in an example.
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Instant answer
The answer appears as you type, with the most important intermediate values.
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See the working
Under "How it's worked out" you see the steps, handy for checking your own calculation.
How it works
Energy in kilowatt-hours (kWh) is power in kilowatts times time in hours. The cost is that energy times the price per kWh.
A 2000 W electric heater that runs 3 hours a day uses 2 × 3 = 6 kWh per day. At 0.30 per kWh that is 1.80 a day, 54.75 a month and 657.00 a year. The tool has no currency, so use whichever currency your price is in.
Where to find the power
On the rating plate or in the manual, usually in watts (W). If it says kW, type for instance 2 kW. Some appliances, such as a fridge or a washing machine, don't run at full power all the time; use the average, or measure it with a plug-in energy meter.
Typical values to start from
| Appliance | Power |
|---|---|
| LED bulb | 8 W |
| Laptop | 50 W |
| Television | 100 W |
| Kettle | 2000 W |
| Hair dryer | 1800 W |
| Electric heater | 2000 W |
These are indications; look at your own appliance for the real figure.
Price per kWh
Use the price including tax from your energy bill. Standing charges are not included, only the energy used. A month is calculated as one twelfth of 365 days.
Want to know how many amps an appliance draws? Use watts to amps.
What running costs add up to
At 0.30 per kWh and these hours per day:
| Appliance | Power | Hours | Per year |
|---|---|---|---|
| LED bulb | 8 W | 5 | 4.38 |
| Laptop | 50 W | 8 | 43.80 |
| Television | 100 W | 4 | 43.80 |
| Electric heater | 2000 W | 3 | 657.00 |
A bulb costs next to nothing, while a heater at 2000 W costs 15 times as much as a laptop that runs 8 hours a day. The big costs are heating and hot water, so that is where to look first.
Compare two devices
Run the calculator for the old and the new appliance with the same hours and price. A 150 W old device at 4 hours a day costs 65.70 a year, a 60 W newer one 26.28, a saving of 39.42 per year. See percentage calculator for how much that is as a share of the price of a replacement.
From watts to a circuit
An appliance of 2000 W draws about 8.7 A on 230 V. The amps to watts calculator does the opposite conversion, and watts to amps gives the current for a breaker.
Frequently asked questions
What is a kWh?
A kilowatt-hour is the energy of 1000 watts running for one hour. A 100 W television watched for 10 hours uses 1 kWh. Your energy bill charges per kWh.
Does the result include the standing charge?
No. It only counts the energy the appliance uses. Fixed monthly or daily fees from your supplier come on top.
How do I include standby power?
Treat standby as a second appliance. A device that sips 5 W around the clock uses 0.12 kWh a day, 43.8 kWh a year and costs 13.14 a year at 0.30 per kWh.
How can I measure the real consumption?
Plug the appliance into a plug-in energy meter for a day or a week and divide by the hours. Fridges and washing machines cycle on and off, so their average power is lower than the rating plate.