Every plug-in heater is exactly 100% efficient, whatever the box claims — so the running cost isn't about the gadget, it's about how much space you heat and for how long. Tell us the room, your rate and who actually needs to be warm, and we'll show the honest cost per evening of every option — including the heat-the-human ones that cost a tenth of heating the room.
This is the biggest lever in the whole sum — bigger than any heater choice. Warming one person costs a fraction of warming the air in a whole room.
Room size and insulation set how much heat the room actually needs; your unit rate prices every kilowatt-hour. Use the rate off your own bill.
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| Option | Draws | Per hour | Per evening | Per winter |
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Heaters without a real thermostat (halogen bars, most fan heaters on low/high switches) run at their setting flat out. Radiant options (halogen, infrared) make you feel warm at a slightly lower air temperature — we credit infrared panels ~15% for that, no more, because the physics doesn't allow more.
Do the free things first. Draught-proof the door and windows of the room you actually sit in, close the curtains at dusk, and shut the doors to rooms you're not heating — a draughty room can need nearly twice the heat of a snug one, and that difference is bigger than any heater choice on this page. And ignore any heater marketed as “eco”, “low energy” or “German engineering” that claims to beat the others on running cost: every electric heater turns 100% of its electricity into heat — a dearer box cannot change that, only its size, thermostat and how it targets the heat can. If the whole house is cold every evening, the real fix is insulation and heating upgrades — our SEAI grant checkers cover what's funded.
A heated throw and a right-sized thermostatted heater cover almost every situation between them — and both cost less than a month of heating a room you didn't need to heat.
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Every euro figure is computed from the unit rate you enter — the tool invents no prices. The fixed assumptions are planning anchors: room heat requirement of 55/75/110 W/m² for snug/average/draughty rooms; typical appliance wattages (heated throw 100 W, electric blanket 60 W, halogen bar 1,200 W, infrared panel 900 W, panel heater 1,500 W, oil-filled radiator and fan heater 2,000 W); thermostatted heaters costed at the room's requirement rather than their maximum once the room is warm; a 15% radiant comfort credit for infrared panels; and a 150-evening November–March winter. Real rooms vary with ceiling height, glazing and weather — treat the results as honest comparisons of scale, not bills to the cent. Figures last reviewed July 2026 — check your own unit rate, which is what everything here scales from.
Trick answer: the cheapest option is usually not to heat the room at all, but the people in it. A heated throw at ~100 W costs a few cents an evening; holding an average 20 m² living room warm takes ~1.5 kW — fifteen times the power, whatever heater supplies it. If several people use the room and you do need the air warm, then any thermostatted heater big enough for the room costs roughly the same to run — pick on comfort, speed and noise, not on running-cost claims.
Per unit of heat, no — and this is the most-marketed myth in the category. Every electric resistance heater converts 100% of the electricity it draws into heat; a €30 fan heater and a €300 designer panel are identical on that score. Radiant types (halogen, infrared) have one honest advantage: they warm you directly, so you can feel comfortable with the air a degree or two cooler — worth maybe 10–15%, and we credit it. Anything promising 30–50% savings over other electric heaters is physics-free marketing.
Running cost is near-identical once the room is warm, because both are thermostatted and both average the room's requirement. The real differences: a fan heater heats the air fast but is noisy and stops mattering the second it switches off; an oil-filled radiator is slow to start, silent, and keeps radiating after the thermostat cuts — much nicer for a 3+ hour evening. Rule of thumb: quick bursts → fan; long sessions → oil-filled.
Around 2–4 cents an hour at current Irish rates — a 60 W blanket for an hour before bed costs about 2c, and even all night is under 20c. It's the single best cost-per-comfort purchase in this whole comparison, which is why the bed scenario recommends it without hesitation. Modern ones with overheat protection and timers are safe when used per the instructions and replaced when worn.
For one room, usually yes: gas or oil heat costs roughly 13–14c per useful kWh against ~36c for day-rate electricity, but the boiler heats the whole house — so warming six rooms to use one costs more than one electric heater in one room. The crossover comes around two to three rooms in regular evening use: beyond that, run the heating (ideally with the radiators turned off in empty rooms). If you have a heat pump, its heat costs ~10c/kWh and it wins for the whole house almost regardless.
A few real safety points: never run a fan or halogen heater unattended, near curtains or bedding, or while asleep; don't dry clothes on any heater; buy heaters and blankets with a CE/UKCA mark and an overheat cut-out, and retire frayed blankets. And never use a gas camping stove, barbecue or patio heater indoors for warmth — carbon monoxide kills people in Ireland every winter. If cost is forcing that kind of choice, contact SVP or check your eligibility for the Fuel Allowance — that side of things has no place carrying affiliate links, so we simply point you there.