What an electric heater cost actually looks like on paper
Every autumn, the same question does the rounds: is it cheaper to run one small heater in the room you’re actually sitting in, or just put the central heating on for the whole house? The honest answer is that electric heater cost depends entirely on the size of the heater and how long it runs, so let’s do the sums properly rather than guessing. Grab whichever heater you actually own, check the label, and the numbers below will make a lot more sense.
From October 2026, Ofgem’s price cap sets the average electricity unit rate at 26.32p per kWh for a typical direct debit household. That’s the number every electric heater cost calculation in this piece is built on, so if your own tariff differs, adjust accordingly.
How do you work out electric heater cost per hour?
The maths is simpler than it looks. Take your heater’s wattage, divide by 1,000 to get kilowatts, then multiply by the unit rate. A 1kW fan heater running flat out for an hour uses 1kWh, so at 26.32p per kWh, that’s roughly 26p an hour.
Step it up to a 2kW oil-filled radiator or a fan heater on its highest setting, and you’re looking at around 53p an hour. A larger 2.5kW convector heater comes in at roughly 66p an hour. None of these numbers are exact for your home, since actual usage depends on the thermostat cycling on and off, but they’re a solid working estimate.
Type matters less than wattage, but it’s worth a mention. A fan heater heats the air quickly but stops the moment it’s switched off. An oil-filled radiator takes longer to warm up but keeps radiating heat for a while afterwards, which can mean a similar electric heater cost overall despite feeling different in the room. Infrared panel heaters warm objects and people directly rather than the air, so they can feel effective at a lower wattage in a draughty space.
Multiply the hourly figure out and the picture gets clearer. A 2kW heater run for four hours a night, five nights a week, comes to roughly £10.50 a week on these rates, purely for that one heater. That’s the kind of number worth knowing before winter properly sets in, not after the first bill arrives.
Is electric heater cost cheaper than central heating?
For heating one room for a short burst, often yes. If you’re only in the living room for the evening and the rest of the house is empty, a single 1kW heater for three hours costs around 79p, against the standing charge and gas usage of firing up a whole central heating system for the same window. That gap tends to be biggest in a small flat or a single occupied room in an otherwise empty house.
For heating a full house over a long evening, electric heater cost usually loses. Gas is typically cheaper per unit of heat than electricity, and a house full of heaters running for hours adds up fast. The honest rule of thumb: electric heaters are a good top-up, not a full replacement for central heating in a cold house. Our average energy bill guide has the fuller picture of what a typical household pays across a whole year.
Key takeaways
- From October 2026, Ofgem’s average unit rate is around 26.32p per kWh for electricity.
- A 1kW heater costs roughly 26p an hour to run; a 2kW heater roughly 53p an hour.
- Electric heater cost usually beats central heating for one room, short bursts.
- Electric heater cost usually loses to central heating for a whole house, long stretches.
- Check the wattage label on your own heater rather than assuming a typical figure applies.
3 checks to keep electric heater cost under control
Roo’s rule of thumb: if you wouldn’t leave a kettle boiling in an empty room, don’t leave a heater running in one either.
First, check the wattage on the heater itself, usually printed on a label near the plug or in the manual. Electric heater cost scales directly with wattage, so a bigger number means a bigger bill per hour, no way around it.
Second, use a timer or thermostat setting rather than running a heater continuously. Even cheap plug-in heaters often have one, and it’s the single easiest way to stop electric heater cost creeping up while you’re not even in the room. It sounds obvious written down, and yet it’s the check most people skip when they’re cold and just want the room warm.
Third, weigh up the room, not just the heater. A small draughty room with a heater working against an open door racks up electric heater cost fast, so it’s worth reading our guide on when to turn your heating on before you reach for the heater at all.
Frequently asked questions about electric heater cost
- Which type of electric heater is cheapest to run?
- The lowest-wattage heater that still keeps you warm. A 1kW heater always costs less per hour than a 2.5kW one, regardless of style or brand.
- Do oil-filled radiators cost more than fan heaters?
- Not necessarily. Cost depends on wattage, not type, though oil-filled radiators often hold heat for longer after switching off, which can even out the running cost over an evening.
- Is it cheaper to heat one room than the whole house?
- Usually, if you’re only using that one room. Once you’re heating most of the house anyway, central heating tends to work out cheaper per unit of warmth.
- How do I calculate electric heater cost for my own tariff?
- Divide the heater’s wattage by 1,000, then multiply by your unit rate in pence per kWh. That gives you the cost per hour of continuous use.
- Does a heater’s thermostat reduce the running cost?
- Yes. A heater cycling on and off to maintain a set temperature uses less electricity overall than one left running on full power constantly.
