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Electricity cost calculator - appliance energy use and cost

Add devices from the list or enter your own wattage and hours of use. The calculator adds up the kWh per month and year and the cost at your electricity rate, including standby power.

  • Free
  • No sign-up
  • Private
  • Runs locally
$/kWh

Example price (a typical US residential rate including delivery). Enter the all-in rate per kWh from your own bill for an accurate result.

Devices

E.g. a fridge compressor runs only about 30% of the time.

Monthly use
88.8 kWh
Monthly cost
$15.98
Yearly use
1,065.5 kWh
Yearly cost
$191.79

Breakdown by device

DevicekWh / monthCost / monthCost / year
Refrigerator21.6$3.89$46.66
Electric kettle18$3.24$38.88
TV12.3$2.21$26.57
Desktop computer27.5$4.96$59.49
Washing machine9.4$1.68$20.20
Total88.8$15.98$191.79

Calculations assume 30 days per month and 12 months per year. Power and hours are typical values, not measurements - enter data for your own devices (rating plate or a plug-in watt meter) for accuracy.

This is an estimate. A real electricity bill also includes fixed charges (such as a daily standing charge or monthly customer charge) and taxes, so the amount on the bill will be higher than the cost of the energy used.

Results are for information only and are not legal, tax or financial advice.

How to calculate the cost of running an appliance

  1. 1.

    Enter your electricity rate

    Type the price per kWh from your bill. Use the all-in rate including delivery and taxes, not just the energy charge.

  2. 2.

    Add your devices

    Choose them from the list (fridge, kettle, washing machine, TV, PC and more) or add a custom device with its own wattage.

  3. 3.

    Adjust the usage

    Set the hours per day, days per month and average load - a fridge compressor, for example, runs only about 30% of the time.

  4. 4.

    Read the result

    You see kWh and cost per month and per year, plus a breakdown by device. You can copy the summary.

How to calculate electricity use

The basic formula is simple: kWh = power [W] × hours of use ÷ 1000, and cost = kWh × price per kWh. For example, a 2,000 W kettle running 18 minutes a day (0.3 h) uses 2,000 × 0.3 ÷ 1,000 = 0.6 kWh a day, or 18 kWh a month. At $0.18 per kWh that is $3.24 a month.

Many appliances do not run at full power the whole time they are on. A fridge compressor cycles on and off, an oven holds its temperature, and an induction hob rarely runs all zones at maximum. That is what the average load field is for: kWh = W × load × hours ÷ 1000.

With the five default devices (fridge, kettle, TV, desktop PC and washing machine) and standby included, the total is about 89 kWh a month, which costs about $16 a month or $192 a year at $0.18 per kWh.

Typical power and monthly use

DevicePowerTypical usekWh per month
Fridge100 W (30% load)24 h a dayabout 22
Electric kettle2,000 W18 min a dayabout 18
Desktop PC150 W6 h a dayabout 27
TV100 W4 h a dayabout 12
Washing machine500 W1.5 h, 12 times a monthabout 9
Electric space heater2,000 W (50% load)5 h a dayabout 150
LED bulb8 W5 h a dayabout 1.2

The power rating is on the device label or in the manual. For the most accurate numbers, use a plug-in energy monitor: it shows real consumption, including standby.

Standby power

Many devices draw power even when "off": TVs, consoles, set-top boxes, chargers and appliances with clocks or displays. A single device usually draws 0.5-2 W, but a whole home can add up to 20-50 W around the clock, which is 15-35 kWh a month. Switch on "Include standby consumption" and enter the standby wattage to see how much it costs. Smart power strips and switching devices off at the wall are the simplest ways to cut it.

Why your bill is higher than the result

The calculator shows the cost of the energy you use. A real bill also includes fixed charges, such as a daily standing charge or monthly customer charge, plus taxes and sometimes peak or time-of-use rates. Divide your last bill's total by the kWh used to get an all-in rate that you can enter here. The calculator assumes 30 days a month and 12 months a year.

For the cost of a car journey, including an electric car, see the trip cost calculator.

Frequently asked questions

How do I convert watts to kWh?

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Multiply the power in watts by the hours of use and divide by 1,000. A 100 W device running for 10 hours uses 1 kWh.

How much electricity does a fridge use?

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A modern fridge uses about 0.5-1 kWh a day, roughly 15-30 kWh a month. Its compressor runs only part of the time, which is why the calculator uses a 30% load.

How much does it cost to run a 2,000 W heater?

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At full power it uses 2 kWh per hour. At $0.18 per kWh that is $0.36 an hour; 5 hours a day at a 50% average load costs about $27 a month.

What electricity price should I enter?

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Use the all-in rate per kWh from your bill, including delivery and taxes. You can work it out by dividing the bill total by the kWh used.

Is standby power worth worrying about?

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Individually it is small, but 20-50 W across a home running all day adds 15-35 kWh a month. Switching devices off at the wall removes it.

Can I use a currency other than dollars?

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The result is shown in dollars, but the maths is the same in any currency. Enter your rate in pounds, euros or zloty and read the figures in that currency.

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