The cheapest way to heat a room

There's no such thing as a cheaper watt

A watt of heat from a $20 fan heater and a watt of heat from a premium ceramic space heater cost exactly the same to run, because both convert electricity to heat at essentially 100% efficiency. Any product claiming to make heat 'more efficiently' than a plain resistance element is describing marketing, not physics.

What actually changes the bill is how much of that heat you waste — heating a whole house when you're sitting in one room, running longer than needed because the room leaks warmth, or leaving a unit on with nobody in the room.

How we work these figures out

For any electric heater, cost per hour is watts ÷ 1000 × price per kWh. An 800W heater at $0.17/kWh costs 0.8 × 0.17 = $0.136/hour, or about $1.09 for an 8-hour evening. Multiply by the days you actually use it to get a real monthly figure — see the full cost per month breakdown with tables across wattages and rates.

The comparison that actually matters is this hourly heater cost against what your furnace or boiler burns to heat the whole house for the same period — which most utility bills don't break down by room, so it has to be estimated by turning the thermostat down and watching the change.

Step 1: stop the heat leaving before you spend anything

• Close the door of the room you're occupying so you're not heating a hallway too.
• Draw curtains at dusk — glass loses heat fast once it's dark outside.
• Block obvious draughts under doors and around old window frames.
• Move furniture away from radiators or heater airflow paths so warm air actually circulates.

Step 2: heat the room, not the house

Turn the central thermostat down a few degrees and put a plug-in heater in the room you're actually using. The whole-house system then runs less, for fewer hours, while the occupied room stays warmer than the rest of the house. This is the entire mechanism behind space heaters 'saving money' — there is no other one.

It only works if you actually lower the main thermostat. Running a space heater on top of an unchanged central setting adds a cost with nothing offsetting it, which is the single most common mistake in this comparison.

Step 3: control run time, not just power level

A heater is billed by the hour it runs, so a timer and an auto shut-off save more than any wattage decision. WellHeater's touch panel and remote include exactly this — a timer and cool-down mode — precisely because run-time control is where real savings live; see the manual for how to set it.

Heating method comparison

What not to bother with

• Heaters claiming impossible efficiency percentages above 100% — that's not physically possible for a resistance or ceramic element.
• Running a space heater alongside central heating left at full temperature — you pay for both with no offset.
• Buying an oversized unit for a small room — it reaches temperature fast, cycles on and off, and doesn't feel meaningfully warmer.
• Leaving a heater on low all day 'to keep the chill off' in an empty room — that's continuous cost for no comfort gained.

Matching the heater to the room

An oversized heater in a small room doesn't heat it any faster in a way you'll notice, and a thermostat-equipped unit will just cycle more often at the same average cost. Our wattage guide has a room-size table so you're not guessing.

For most bedrooms and home offices under 130 sq ft, an 800W unit like WellHeater is enough to reach comfortable warmth in about a minute without oversizing — see bedroom heater and office desk heater picks for room-specific notes.

When central or gas heating is actually cheaper

If you're heating two or more occupied rooms simultaneously for several hours, a whole-house system often wins on cost per unit of heat, particularly with gas. Zone heating shines specifically when only one room is in use — a bedroom overnight, an office during the day, a bathroom for twenty minutes.