Guide · electrical load

Watts, amps and your circuit

The arithmetic behind why every unit in this category is 1,500 watts, why manufacturers ask for a dedicated circuit, and where our advice stops.

By Scooter M.Published September 2, 2026Last reviewed September 2, 2026

An electrical breaker panel with the door open

The arithmetic

Amps = watts ÷ volts. A 1,500 W fireplace on a 120 V circuit draws 12.5 amps. A standard US branch circuit is 15 amps, and continuous loads are conventionally limited to 80% of that — which is 12 amps. That is why 1,500 W is the ceiling for the entire category, and why manufacturers commonly specify a dedicated circuit.

Setting	Watts	Amps at 120 V	Share of a 15 A circuit
Flame only	~100 W	0.8 A	About 6%
Low heat	750 W	6.3 A	About 42%
Full heat	1,500 W	12.5 A	About 83%

The 83% figure is why nothing else meaningful should share the circuit while the heater runs.

What that means in your house

A 15-amp circuit in a typical American living room may already be carrying a television, a streaming box, a soundbar, lamps and a phone charger. Individually those are small. Add a 12.5 amp continuous load and the circuit is at or over its practical limit, and the breaker will eventually tell you so — usually on the coldest evening of the year.

This is also the reason every manufacturer says not to use an extension cord or a power strip. It is not fussiness. A 12.5 amp continuous draw through a cord not rated for it is a genuine ignition source, and it is the failure mode behind a meaningful share of heater-related fires.

The rules to actually follow

Plug directly into a wall receptacle. No extension cord, no power strip, no multi-outlet adapter.
Know what else is on the circuit. Switch the fireplace on at full heat, then run the other things on that wall. If the breaker trips, you have your answer.
Use the low setting when it is enough. 750 W is 6.3 amps — less than half the load, and half the running cost.
Do not run it under a rug or behind furniture. Cord damage plus continuous high current is exactly the combination to avoid.
Read the manual for your unit. If it specifies a dedicated circuit, treat that as a requirement rather than a suggestion.

Why you cannot buy a bigger one

Because the constraint is the receptacle. To exceed 1,500 W you need a 240 V circuit and a hardwired appliance — which exists, is a different product category, and requires an electrician and usually a permit. Everything sold as a plug-in electric fireplace in the United States stops at 1,500 W for this reason and no other.

So when you see two units at very different prices both rated 1,500 W, that is not one of them under-delivering. It is both of them hitting the same wall. The full consequence for shopping is on do they actually heat a room.

What the load costs

What a 1,500 watt electric fireplace costs to run at 18.34 cents per kilowatt-hour
Usage	Hours	Heat on (1,500 W)	Flame only (~100 W)
One evening	4	$1.10	$0.07
A week of evenings	28	$7.70	$0.51
A month, 4 hrs a night	120	$33.01	$2.20
A 90-day winter, 4 hrs a night	360	$99.04	$6.60
Per hour	1	27.5¢	1.8¢

At 12.5 A continuous. Computed as (watts ÷ 1000) × rate, at 18.34¢/kWh — the US residential average from EIA Electric Power Monthly, Table 5.3 (June 2026), released 2026-08-26. Your rate is on your own bill — put it into the calculator. The flame-only column assumes a conservative 100 W for the LED assembly with the heater switched off.

Work out your own running cost

Four numbers, no email address. The rate defaults to the US residential average; the number that matters is the one on your own bill.

Rated watts

1,500 W is the 120 V ceiling.

Your rate (¢ per kWh)

US average: 18.34¢.

Hours a night

Nights in the season

Per hour: 27.5¢
A month at this usage: $33.01
The whole season: $99.04

At 1,500 W this unit produces about 5,118 BTU/hr and draws 12.5 A on a 120 V circuit. The formula is (watts ÷ 1000) × rate, applied for the hours you entered — the same function that renders every cost figure elsewhere on this site. Default rate from EIA Electric Power Monthly, Table 5.3 (June 2026).

Questions people actually ask

How many amps does an electric fireplace draw?

About 12.5 amps at 1,500 W on a 120 V circuit — amps equals watts divided by volts. On a 750 W low setting it is about 6.3 amps.

Does an electric fireplace need a dedicated circuit?

Many manufacturers specify one, because 12.5 amps is roughly 83% of a 15-amp circuit before anything else is plugged in. Whether you need to add one depends on what else shares that circuit in your house — an electrician can tell you quickly.

Can I plug an electric fireplace into a power strip?

No. Manufacturers prohibit it and the reason is sound: a continuous 12.5 amp load through a strip or extension cord not rated for it is a real fire risk. Wall receptacle only.

Will an electric fireplace trip my breaker?

It can, if the circuit is already loaded. At full heat it uses about 83% of a 15-amp circuit on its own. Test it: run the fireplace on high, then switch on everything else on that wall, and see what happens before you rely on it in January.

Why are all electric fireplaces 1500 watts?

Because 1,500 W at 120 V is 12.5 amps, which is the practical continuous limit for a standard 15-amp household circuit. Exceeding it requires 240 V hardwired equipment, which is a different category entirely.

Sources

Every figure on this page is either taken from one of these documents or computed from a formula shown on the page. Nothing here is recalled from memory.