Heater & dehumidifier running cost calculator (Ireland)
Work out what a plug-in heater or a dehumidifier will add to your electricity bill this winter, at Irish rates — and see which of the 38 models we compare gives you the most for your money. Change any number and the results update instantly.
Ranked by total first-winter cost (price + electricity) among heaters big enough for the room. Heaters we compare but whose wattage is not published are left out rather than guessed: none.
Ranked by electricity cost per litre of rated extraction — the fairest way to compare a small unit with a big one. Costs assume the compressor runs the whole time; a humidistat switches it off once the room is dry, so real bills are lower. Left out (no published wattage): EasyAcc 2000ml Dehumidifier Pro, Morphy Richards PureFresh Compact Dehumidifier, UniBond AERO 360 Moisture Absorber, ROMMQB 3L Ultra-Quiet Portable Dehumidifier, Devology 12L/Day Digital Dehumidifier (2.5L Tank).
How the calculator works
Electricity rate
We use a domestic day rate of €0.38/kWh and a smart-meter night rate of €0.18/kWh (July 2026), cross-checked against SEAI price statistics and supplier standard rates. Pick “My own rate” to use the figure on your bill.
Heater size
Room size × a watts-per-m² rule of thumb: 45 W/m² for a well-insulated room, 70 for an average one, 100 for a draughty one. It is the size needed on the coldest days, not what you burn every hour.
Heater running cost
Size needed × hours × the share of that heat you need on an average day (60% by default) × days × rate. A heater big enough for the room reaches temperature and its thermostat cycles, so this cost is the same for every adequate heater. A heater that is too small runs at full power for every hour and the room never gets warm — we show that cost too, greyed out.
Dehumidifier running cost
Rated wattage × hours × days × rate, as a ceiling. Cost per litre = one day at full power ÷ rated litres per day. Wattages and extraction figures come from manufacturer specifications on each product page; nothing is estimated.
Frequently asked questions
How much does it cost to run a 2kW heater in Ireland?
At a day rate of €0.38/kWh a 2kW heater costs €0.76 per hour at full power. With a thermostat it draws full power only part of the time, so the real cost is lower. On a night rate of €0.18/kWh the same hour costs €0.36.
Is an oil-filled radiator cheaper to run than a fan heater?
No. Every plug-in electric heater turns close to 100% of the electricity it uses into heat. If two heaters are both big enough for the room, keeping it at the same temperature for the same hours costs the same. Oil radiators feel gentler and keep radiating after they switch off; fan heaters warm the air faster. The difference is comfort and purchase price, not the bill.
What size heater do I need for my room?
A common installer rule of thumb is about 45 W per m² in a well-insulated room, 70 W/m² in an average one and 100 W/m² in a draughty one. A 12 m² room of average insulation needs roughly 840 W. A heater smaller than that runs at full power without ever reaching temperature.
How much does a dehumidifier cost to run in Ireland?
The 12 L/day dehumidifiers we compare draw 136–210 W, which is about €0.05–€0.08 per hour at €0.38/kWh. Running 8 hours a day for a 26-week winter that is at most €75–€116, and less once the humidistat cycles.
Which dehumidifier removes the most water per euro?
Of the models we compare, the MeacoDry Arete Two 12L Dehumidifier & Air Purifier has the lowest electricity cost per litre of rated extraction (€0.103 per litre at €0.38/kWh). Rated extraction is measured at warm, very humid test conditions, so real-world litres in an Irish winter are lower for every model — the ranking still holds.
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