How Much Does a Space Heater Cost to Run?

By Yasir Siraj · Last updated 21 October 2026

A 1,500-watt space heater running eight hours a day adds 360 kWh to your monthly electricity use. At Massachusetts's average rate over the past twelve months that is about $109.40 a month. A typical Massachusetts household uses 603 kWh in total, so running one heater adds roughly 60% to everything that household already consumes.

The assumptions throughout this page are simple: 1,500 watts, eight hours a day, thirty days. That is 360 kWh. Run the heater four hours a day and the figure falls to 180 kWh. Run it continuously and it rises to 1,080 kWh a month. Your actual cost depends on your electricity rate and how long the heater runs.

What it costs where you live

The same heater can cost more than twice as much to run in one state as in another. At the rates above it comes to about $116.42 a month in California against roughly $46.87 in Louisiana. Neither the heater nor its schedule changes; the electricity rate does.

Setting that against the whole household bill makes the difference easier to feel. In California the heater is about 74% of the state's average monthly residential bill. In Louisiana it is about 30%. One caution on that comparison: the fourth column is the state's average bill for everything, not a heating bill, and the two figures do not come from the same household or the same heating habits.

Why "just heat one room" often costs more

A space heater can warm one room without heating the rest of the house, and that does not automatically make it cheaper. Most portable electric heaters use resistance heating: electricity passes through an element and becomes heat. At the point of use nearly all the electricity consumed turns into heat in the room — but the heater cannot deliver several units of heat for every unit of electricity it draws.

A heat pump works differently. Rather than generating heat it moves heat from outside into the house, which lets it deliver several units of warmth per unit of electricity. The U.S. Department of Energy puts the difference at roughly two thirds.

So if your home already has a heat pump, heating with a resistance space heater instead can use substantially more electricity for comparable warmth. The exact difference depends on the equipment and the conditions it runs in. Gas may also cost less per unit of useful heat, but that turns on local gas prices and system efficiency, and this site does not track gas prices — so I am not going to tell you gas is cheaper everywhere.

When it actually does save money

There is a case where heating one room genuinely saves: you turn the main thermostat down and use the space heater only in the room you are occupying. The rest of the house gets cooler, so the main heating system does less work. The heater adds electricity, and some of that is offset by the heating you are no longer buying.

It is far less likely to save anything when the heater runs alongside normal heating. If the central system or heat pump is still holding the whole house at the same temperature, the heater is being added to your energy use rather than replacing any of it. That is the common case, and it is why the January bill is a surprise.

So the question is not really whether you are heating one room. It is whether the rest of the house got colder. A space heater is genuinely useful for targeted comfort — but if it runs on top of your usual heating without reducing the work your main system does, it adds to the bill rather than replacing anything on it.

What to check on your own bill

Your own bill can tell you roughly how much extra electricity winter heating is using. Compare the kWh on a winter bill against a mild month such as October and take the difference. It is only an estimate: weather, how many people are home and everything else in the house all move that number too.

For scale, a 1,500-watt heater at eight hours a day for thirty days is 360 kWh. Divide your increase by 360 and you have the number of equivalent heater-months it represents — an increase of 720 kWh is two of them. That is a unit of measurement, not proof of cause; it does not show a heater produced the whole increase.

• Find your state's rate
• Estimate a bill from your own usage
• Why is my electricity bill so high?
• Why a cheap rate doesn't mean a cheap bill

Every state page carries a CSV of its full monthly history if you want to check the rate yourself. A rate-based estimate will not match your bill exactly. The average rate already includes delivery and the fixed monthly charge, spread across every kWh. The fixed charge does not grow when you add a heater, which pulls the true cost slightly below this table; a tiered rate that prices extra kWh in a higher band pushes it above. Sales tax, where your state charges it, is added on top.