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Every plug-in heater gives the same heat. The room size claims do not.
A 1,500 watt space heater gives about 5,118 BTU per hour. That is true of a small ceramic cube, a 23 pound oil-filled radiator and a wood-look infrared cabinet. Yet the listings we read claim anywhere from 150 to 576 square feet for that same output. So start with your room, not the box. If your room needs more than 1,500 watts, no plug-in heater will keep up. If it needs less, pick on the things that really differ: heater type, shutoff switches, thermostat, noise and low settings.
Space heater size and power use calculator
An estimate. The 6 and 8 watts per square foot come from Cadet's sizing article (1,500 W for a 250 sq ft room with central heat, 2,000 W with no other heat). The insulation and ceiling steps are ours. Power use assumes the heater runs at full power the whole time. A thermostat that cycles off will use less.
Check your room against 1,500 watts See the 7 picks
Guides
Start here
- Is one 1,500 watt heater enough for your room?
Enter room size, ceiling, insulation and hours. See the watts your room needs, whether one 1,500 W heater can cover it, and the kWh it will use per day.
- Why almost every plug-in heater stops at 1,500 watts
Nearly all plug-in space heaters top out at 1,500 watts, 12.5 amps, about 5,100 BTU per hour. Here is why, and why room size claims still differ.
- Ceramic, oil-filled or infrared: same watts, different feel
Ceramic fan, oil-filled radiator and infrared heaters all top out at 1,500 watts. What changes is speed, noise, weight and where the warmth lands.
Safety
- Space heater safety: the rules the fire agencies agree on
What the CPSC, NFPA, ESFI and the U.S. Fire Administration say about space heaters: three feet of clearance, wall outlet only, off when you sleep.
- Why a space heater trips the breaker
A 1,500 watt heater draws 12.5 amps by itself. Why it trips a shared circuit, the warning signs ESFI lists, and what never to do about it.
- How to check a space heater for recalls and safety marks
How to check a space heater against CPSC recalls, what a UL or ETL mark means under OSHA's test lab program, and where to report a problem.
Running it
- What a space heater uses per hour, in kWh
A 1,500 watt heater uses 1.5 kWh per hour at full power. Work out your own cost from your bill's rate, and see what low settings and thermostats change.
More guides
- The 7 best electric space heaters, compared on what really differs
Seven electric space heaters from DREO, Lasko, De'Longhi, Dr Infrared and Amazon Basics, compared on type, shutoff switches, noise claims and room size claims.