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Pick an appliance to load example values, then replace them with the watts on your device's label and your own hours of use. You get the kWh per day, month and year, and the cost if you enter your price.

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Loads example values. Replace them with the figures of your own device.
From the label or manual, in watts (1 kW = 1000 W).
Where do I find this?

The rating plate, the manual or the product page shows W or kW. The examples here are rough starting points, not measurements.

Fridges, freezers and heaters with a thermostat switch on and off. For a fridge, a rule of thumb is to count about a third of the time it is plugged in.

How long it actually runs on a day it is used (0.25 = 15 minutes).
Where do I find this?

Count the time the device really draws power. A kettle used three times a day for 4 minutes runs about 0.2 hours.

A plug-in energy meter measures the real consumption over a few days.

7 for every day, 5 for weekdays only.
Where do I find this?

For a washing machine used four times a week, enter 4 days and the hours of one cycle.

Your electricity price per kWh, from the bill or the tariff.
Where do I find this?

The bill shows the energy price per kWh. Use the price including tax for a realistic cost.

Only changes the symbol; no exchange rate is applied.

Result

Enter your values to see the result.

Use per year
– kWh
Per month
– kWh
Per day of use
– kWh
Cost per year
–
Cost per month
–

Want this tracked for you? UtilityControl logs your meters and costs automatically.

How it is calculated

  • kWh per day of use = watts × hours ÷ 1000
  • kWh per year = kWh per day × days per week × 365 ÷ 7
  • Cost = kWh × price per kWh

Example

A 1500 W space heater running 4 hours a day, every day, uses 1500 × 4 ÷ 1000 = 6 kWh a day, about 2,190 kWh a year. At 0.30 per kWh that is about 657 a year.

What this estimate leaves out

The label shows the maximum power; many devices draw less most of the time, and anything with a thermostat switches on and off. Standby power is not included. For the real figure use a plug-in energy meter or the yearly kWh on the energy label.

Sources: Virginia Cooperative Extension: Estimating appliance and home electronic energy use (fridge rule of thumb)

Written and reviewed by QLines, Cologne · Last reviewed

FAQ

Frequently Asked Questions

How do I calculate how much electricity an appliance uses?

Multiply the power in watts by the hours of use and divide by 1000: that is the kWh. Multiply by your price per kWh for the cost. Example: 100 W × 8 hours ÷ 1000 = 0.8 kWh.

How much electricity does a fridge use?

The energy label states the yearly use in kWh (EU energy label, or the EnergyGuide label in the US). Divide it by 365 for the daily use. Without a label, take the rated watts and about a third of the time it is plugged in.

How much does it cost to run a space heater?

A 1500 W heater uses 1.5 kWh per hour. At 0.30 per kWh that is 0.45 an hour, or about 1.80 for four hours a day.

Why is my measured use lower than the calculation?

The wattage on the label is the maximum. Thermostats, eco modes and partial load mean most devices use less on average. A plug-in meter shows the real figure.

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See UtilityControl Pricing