How many watts does a space heater use? Can a power station run one?

A Lasko ceramic space heater lists 900 to 1,500 watts, so our tools count 1,500 watts for a heater. A power station with enough output can run one, but only for a short time: a box that holds about 1,000 watt-hours runs it for about 35 minutes. Watts: how fast something uses power. Watt-hours: how much power a box holds.

How many watts a space heater uses

Making heat takes a lot of power. The Lasko page gives two numbers, 900 and 1,500 watts, for a heater with two heat settings. It does not say which setting uses which number. So we use the high number, 1,500 watts, to be careful.

Your heater may use more or less. Look for the watts on its label.

A fridge is a good thing to compare. Our tools count 120 watts for a fridge. A heater uses more than 12 times as much. The same box that runs a fridge for about 7.3 hours runs a heater for about 35 minutes.

The easy math

Take the box size in watt-hours. Keep 85% of it, because some power is lost inside the box. Then divide by the heater's watts.

1,024 Wh × 0.85 ÷ 1,500 W = about 0.6 hours

That is the EcoFlow DELTA 3, a box of about 1,000 watt-hours. It comes to about 35 minutes.

Estimates. Your devices may use more or less.

Hours by box size

The first number column uses the high number, 1,500 watts. The second uses the low number from the Lasko page, 900 watts.

Box size	At 1,500 W (about)	At 900 W (about)
About 1,000 Wh (1,024 Wh)	0.6 hours	1.0 hours
About 2,000 Wh (2,048 Wh)	1.2 hours	1.9 hours
About 3,000 Wh (3,014 Wh)	1.7 hours	2.8 hours
About 4,000 Wh (4,096 Wh)	2.3 hours	3.9 hours

Estimates. Your devices may use more or less.

Can your box give the watts?

Hours are only half of it. The box must also be able to send out the watts. Look at its output. The numbers below come from each maker's own page, and "Yes" means on paper.

Box	Output	Runs a 1,500 W heater?
Anker SOLIX C300	300 W	No
EcoFlow RIVER 3 Plus	600 W	No
Jackery Explorer 1000 v2	1,500 W	Yes, with nothing else on
EcoFlow DELTA 3	1,800 W	Yes
Anker SOLIX C2000 Gen 2	2,400 W	Yes

A box with 600 watts of output cannot run a 1,500-watt heater at all, even if it holds a lot of watt-hours. Check output first, then size.

Why this box? It lists 2,400 watts of output and holds about 2,000 watt-hours. That runs a 1,500-watt heater for about 1.2 hours. The extra 900 watts of output leaves room for a phone (20 W) and a router (15 W) on the same box.

Could it run all night?

Eight hours at 900 watts takes about 8,500 watt-hours. At 1,500 watts it takes about 14,100. The largest box we list holds 4,096. So no box we list can run a 900-watt or 1,500-watt heater all night.

Estimates. Your devices may use more or less.

What the same box runs for longer

A box that holds about 1,000 watt-hours does much more with small things. This uses the same math and the watts our tools count for each one.

Thing	Watts	Hours on about 1,000 Wh (about)
Wi-Fi router	15 W	58 hours
Phones	20 W	44 hours
Lights	40 W	22 hours
Fan	50 W	17 hours
Laptop	65 W	13 hours
TV	100 W	8.7 hours
Fridge	120 W	7.3 hours
Space heater	1,500 W	0.6 hours

Estimates. Your devices may use more or less.

Tips before cold weather

• Read the label on your heater and write down its watts.
• Check a box's output before its size. The output must be at least the heater's watts.
• Save the box for small things like a router, phones, and lights. They run for many hours.
• Charge the box before a storm, not during it.
• Add up your own list with Find My Power.

New to these words? Read what a watt-hour is and watts vs watt-hours. To plan more than one thing, see our whole-home backup guide, the picks page, or Compare. See how we check each number. Want to compare boxes? See the 1,000 watt-hour comparison or the 2,000 watt-hour comparison.

Questions people ask

How many watts does a space heater use?

It depends on the model. Lasko lists 900 to 1,500 watts for one ceramic heater. Our tools count 1,500 watts. Check the label on yours.

Can a power station run a space heater?

Yes, if its output is at least the heater's watts. It will not last long. A box that holds about 1,000 watt-hours runs a 1,500-watt heater for about 35 minutes.

Can a small power station run a small heater?

Only if the heater uses no more watts than the box's output. A box with 600 watts of output cannot run a heater that uses 900 watts. Check the label on your heater.

What can a box run for much longer?

Things that sip power. A box that holds about 1,000 watt-hours runs a Wi-Fi router for about 58 hours at 15 watts. It runs phones for about 44 hours at 20 watts.