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Running-cost calculator: what does it cost to run?

Last checked November 2026. Offers and rules change: confirm with the provider before you rely on them.

Any electrical appliance costs its wattage, times the hours you use it, times what you pay for a unit of electricity. Put in those three numbers and this calculator shows the cost per hour, per day, per week and per month.

Rough typical figures. The real one is on the rating plate or label of your appliance, shown in watts (W) or kilowatts (kW). 1kW is 1,000W.
For a kettle, 3 minutes is 0.05 hours.
On your bill or tariff as "unit rate".

How the sum works

  1. Divide the wattage by 1,000 to get kilowatts. A 100W heated throw is 0.1kW.
  2. Multiply by the hours you use it. Four hours at 0.1kW is 0.4 units (kilowatt-hours, or kWh).
  3. Multiply by your unit price. At 25p a unit, 0.4 units costs 10p.
Tip: Heating a person costs far less than heating a room. A heated throw or electric blanket uses a fraction of the power of a fan heater, which is why they feature in our guide to keeping warm for less. They are an extra, though, not a reason to let a room get cold.

What the calculator does not know

  • Thermostats. Heaters, ovens and irons switch on and off to hold a temperature, so they use less than their full wattage over an hour. The result is the most it could cost.
  • Settings. A heated throw on low uses much less than on high. The label shows the maximum.
  • Standing charge. You pay a fixed daily amount whatever you use. It is not included here.
  • Time-of-use tariffs. If you pay different rates by day and night, use the rate for the hours you run the appliance.

See also heated throws and electric blankets, energy-saving tips and choosing an energy tariff. If you are struggling with bills, check Warm Home Discount, Winter Fuel Payment and the Priority Services Register.

Common questions

Where do I find my unit price?

On your electricity bill or your supplier's online account, listed as the unit rate in pence per kWh. It differs by region, by tariff and by how you pay.

Where do I find the wattage of an appliance?

On the rating plate or label, usually on the back or underside, or in the instruction booklet. It is shown in watts (W) or kilowatts (kW).

Is it cheaper to use a heated throw than to put the heating on?

A throw costs much less to run than heating a whole room, but it only warms you, not the room. Health guidance is to keep the rooms you use warm enough, so treat a throw as a top-up.

Does leaving things on standby cost much?

Each item uses very little, usually a watt or less on modern equipment, but several left on all year add up. Enter 1 watt for 24 hours to see what one item costs you.

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