The physics here is simple and exact; the cost isn’t, because it depends on a number we don’t have — your electricity tariff.
The calculation itself
A 2000 W heater run at full power for one hour uses exactly 2 kWh. Multiply that by your own price per kWh — printed on your electricity bill or available from your supplier — for a genuinely accurate running cost.
Most heaters don’t run at full power constantly
A thermostat-controlled heater like the Dreo Atom 316 cycles on and off, or reduces output, once a room reaches its target temperature — actual average draw over an evening is typically well below the full 2000 W figure, though we won’t estimate by how much without real data.
ECO and lower settings reduce draw directly
Where available, a lower wattage setting or an ECO mode reduces draw proportionally — running at 1000 W instead of 2000 W for the same duration genuinely halves the energy used, at the cost of slower heating.
Comparing heaters on running cost
Two heaters of different wattage cost proportionally different amounts to run at full power for the same time — a 1000 W heater costs half what a 2000 W heater does per hour, all else equal. Factor this alongside purchase price when comparing options.
What we would not do
Publish an assumed cost-per-night or cost-per-day figure based on a guessed electricity price. That number would be wrong for most readers almost immediately — the watts-times-hours-times-your-tariff calculation is the only honest way to get a real figure.
Check your own manual before you follow anything here. Humidity ranges, wattages, voltage and current ratings differ from model to model, and the manufacturer's figures take precedence over anything written on this site. We report what makers and monitors publish — a target humidity percentage, a heater's tip-over and overheat protection, a plug or thermostat's maximum load rating — and we never turn a reading into a health verdict or a diagnosis. Questions about air quality and health are matters for a qualified professional and your national health authority, and this site points you to them rather than restating them. Where wiring, voltage or load ratings are involved, matching them exactly to your appliance is a safety matter, not a technicality.
The questions that keep coming up
Why won’t you just publish a cost-per-hour figure?
Because electricity tariffs vary enormously by country and by contract, and any single figure we published would be wrong for most readers within months. The watts-to-kWh math is simple and accurate; the price per kWh is the number only your own bill can give you.
Last reviewed 24 August 2026