How much does it cost to run an electric heater?
Work out what any appliance costs to run per use, per month and per year on your own electricity rate — including what it draws on standby.
Using the Portuguese average of 24.35c/kWh — Eurostat, the second half of 2025.
Every electric heater is 100% efficient, so a 2 kW fan heater, oil filled radiator and halogen heater all cost the same per hour.
Common cases
What drives the cost
Every electric heater is 100% efficient, and that is not marketing — all the electricity ends up as heat in the room, whatever the technology. A 2 kW fan heater, a 2 kW oil-filled radiator and a 2 kW halogen heater cost exactly the same per hour to run. What differs is how the heat feels and how quickly you notice it, not how much you pay.
This is why the only real savings are heating a smaller space, for less time, or with something that is not a resistive heater at all. A heat pump is the exception to the efficiency rule: it moves heat rather than making it, and delivers roughly three units of heat per unit of electricity, which is why it costs about a third as much for the same warmth.
How this is worked out
Electricity is billed per kilowatt hour. An appliance's kilowatt hours are its power in kilowatts multiplied by the hours it runs — so a 2,000 W appliance running for 30 minutes uses 1 kWh. Multiply that by your unit rate and you have the cost. The standing charge is not included here because you pay it whether or not you switch anything on.
What this assumes
- The appliance draws its rated power for the whole time it is on. Anything thermostatically controlled — ovens, heaters, fridges — cycles on and off, so the real figure is lower.
- Your unit rate stays flat all day. On a time-of-use tariff the same appliance costs materially different amounts depending on when you run it.
- A year is 52 weeks of identical use, which overstates seasonal appliances and understates ones you use in bursts.
- The rate filled in for you is an average that spreads fixed charges across a year's usage, so it sits above what one extra unit really costs. Entering the unit rate from your own bill gives a closer answer.
Questions
Which type of electric heater is cheapest to run?
None of them — at the same wattage they all cost the same per hour. Claims otherwise are about comfort or how quickly a room feels warm, not about energy. The genuine difference is a heat pump, which is not a resistive heater.
Is it cheaper to heat one room than the whole house?
Often, yes, if you genuinely only occupy one room. A 2 kW heater in a home office usually costs less per hour than running central heating for the whole house — but it is a poor deal if the rest of the house then gets cold enough to need heating anyway.
Does this include the standing charge?
No, and deliberately. The standing charge is a fixed daily fee for being connected at all, so it does not change when you run an appliance more or less. Including it would make every appliance look more expensive than it is.
Where do I find the wattage?
On the rating plate — usually a sticker on the back, base or inside the door — or in the manual. It is written as W or kW. If it only quotes amps, multiply amps by 230 to get watts.
Why is my bill higher than the total this gives?
Because this prices one appliance. Heating, hot water and the constant background draw of everything left plugged in usually make up more of a bill than the appliances people think to check.
Sources
- Ofgem — price cap unit rates — checked 2026-08-21
- Energy Saving Trust — quick tips to save energy — checked 2026-08-21
Rates from Eurostat for the second half of 2025. Last reviewed 3 September 2026.