Space Heater Cost Calculator

A space heater's daily cost equals its kilowatts times hours run times your rate. A 1,500-watt heater running 8 hours a day uses 12 kWh. At $0.17/kWh that is $2.04 a day, about $61 a month and $745 a year if run every day. The calculator above gives your exact figures once you enter your own rate.

Electric space heaters feel cheap to buy but are expensive to run, because they draw a lot of power — typically 750 to 1,500 watts — and often run for hours. At the maximum 1,500-watt setting a heater uses 1.5 kWh every hour, so cost adds up fast. Since you enter your own electricity rate, this tool shows what heating really costs on your utility, which is essential for deciding whether a space heater or your central system is the cheaper choice.

Electric resistance heaters make the math clean because they convert essentially 100% of the electricity they draw into heat:

Working the standard 1,500 W example:

• Kilowatts: 1,500 ÷ 1000 = 1.5 kW.
• Energy per day: 1.5 kW × 8 h = 12 kWh.
• Daily cost: 12 kWh × $0.17 = $2.04.
• Monthly: $2.04 × 30 = $61.20. Yearly (if daily): $2.04 × 365 = $744.60.

The key fact is that a heater's wattage equals its heat output — a 1,500 W heater delivers 1,500 W (about 5,120 BTU/h) of heat. There is no efficiency multiplier to worry about, unlike a heat pump, which can deliver 2–4× as much heat per kWh. That distinction (covered below) is the single biggest lever on winter heating cost. To price other appliances the same way, use the electricity cost calculator, and to see energy in kWh alone use the energy usage calculator.

These examples show how heater size, run-time, and rate shape the cost.

Example 1 — A 1,500 W heater in a home office, 8 hours a workday. Energy = 1.5 × 8 = 12 kWh. Cost = 12 × 0.17 = $2.04 a day. Over a 5-day week that is $10.20, and across a 4-month winter of workdays (about 85 days) roughly $173 — for heating one room.

Example 2 — A 750 W heater on low, running 10 hours overnight. Energy = 0.75 × 10 = 7.5 kWh. Cost = 7.5 × 0.17 = $1.28 a night, about $38 a month. Lowering wattage helps, but long hours still accumulate.

Example 3 — Two 1,500 W heaters run 6 hours a day in a high-rate market ($0.31/kWh). Energy = 2 × 1.5 × 6 = 18 kWh. Cost = 18 × 0.31 = $5.58 a day, about $167 a month. In expensive markets, whole-home electric-resistance heating can rival a mortgage payment in deep winter.

Example 4 — A 1,000 W heater on a thermostat, cycling to an equivalent 4 hours a day. Energy = 1.0 × 4 = 4 kWh. Cost = 4 × 0.17 = $0.68 a day, about $20 a month. A thermostat that cycles the heater off dramatically cuts cost versus running full-time.

Whether a space heater is an economical choice depends almost entirely on your electricity rate versus the cost of your alternative heat source — which is exactly why this calculator asks for your rate instead of assuming one.

At $0.11/kWh, running a 1,500 W heater 8 hours a day costs about $1.32 daily; at $0.31/kWh the identical heater costs $3.72 — nearly 3× more. In a cheap-electricity region a space heater used to heat only the room you occupy can be cheaper than firing up central heat for the whole house. In an expensive-electricity region the same strategy can cost more than natural gas or a heat pump. No generic "space heaters cost about X" article can tell you which situation you are in; only your own rate can.

The zone-heating trade-off. The honest comparison is: does heating one room with a space heater cost less than heating the whole house with your central system for the same comfort? Space heaters win when you occupy one room for long stretches and can let the rest of the house cool down. They lose when you try to heat many rooms, since several 1,500 W heaters quickly exceed central-heating cost — and can trip circuit breakers, as each 1,500 W heater draws about 12.5 amps on a 120 V circuit. Enter your real rate and hours here, then compare against your gas or heat-pump cost to make the call for your home. For the electrical side of that 12.5-amp draw, see the AC amps to watts calculator.

The most important thing to understand about electric heating cost is that not all electric heat is equal. An electric resistance space heater is 100% efficient — every watt becomes a watt of heat — but a heat pump is 200–400% "efficient" because it moves existing heat rather than creating it, quantified by its coefficient of performance (COP).

Concretely: to deliver 1,500 W of heat, a resistance heater draws 1,500 W from the wall. A heat pump with a COP of 3 delivers the same 1,500 W of heat while drawing only about 500 W — one-third the electricity and one-third the cost. Over a winter, that difference is hundreds of dollars.

This is why space heaters make sense for occasional, single-room, short-duration heating — a quick warm-up, a rarely used room, a workshop — but rarely for whole-home or all-day heating where a heat pump or efficient central system wins decisively. Use this calculator to price the resistance-heater scenario, then divide by an assumed COP of 2.5–3.5 to estimate what a heat pump would cost for the same heat. The gap is usually eye-opening and often justifies the upgrade. Gas heat is a separate comparison, priced per therm rather than per kWh.

1. Enter the heater wattage. Check the label; most portable heaters are 750 W (low), 1,000 W (medium), or 1,500 W (high). Use the setting you actually run.
2. Enter hours used per day. If the heater runs constantly, use the clock hours. If it is on a thermostat that cycles, use the equivalent full-power hours (often half to two-thirds of the on-time).
3. Enter your electricity rate. Use your blended rate (total bill ÷ kWh) so the cost is real for your utility.
4. Read the results. Daily cost is primary, with monthly and yearly projections and the daily energy in kWh.

To budget a whole heating season rather than a full year, calculate the daily cost here and multiply by the number of cold days you actually run the heater — for example 90 or 120 days rather than 365.

Because a heater's cost is watts × hours × rate, and the wattage is largely fixed by the heat you need, the biggest savings come from reducing hours and improving how efficiently that heat is used.

Use a thermostat and timer. A heater that cycles off once the room is warm can cut run-time by a third or more versus running flat-out. Models with a built-in thermostat pay for themselves quickly.

Zone-heat, do not whole-house-heat. Heat only the room you are in and close the door. Turn down the central thermostat for the rest of the house. This is where space heaters genuinely save money — supplementing, not replacing, central heat.

Seal and insulate the room. Draft-proofing windows and doors and closing curtains keeps heat in, so the heater cycles less. Every hour of run-time you avoid is a direct saving.

Right-size the heater. A 750 W heater in a small, well-sealed room may hold temperature as well as a 1,500 W unit run intermittently, at half the peak draw. And consider the bigger picture: if you heat all winter, a heat pump's 2–4× efficiency can save far more than any tweak to a resistance heater. Model the resistance cost here, then compare. For whole-home energy planning, use the power consumption calculator and the electricity bill calculator.

• Assuming a heater runs at full watts constantly. Thermostatic models cycle; use equivalent hours or you will overestimate cost.
• Believing "energy-saving" heaters use less energy for the same heat. All resistance heaters are 100% efficient — 1,500 W is 1,500 W of heat regardless of brand or marketing. Only heat pumps break this rule.
• Running several heaters to heat the whole house. This usually costs more than central heat and risks overloading circuits (each 1,500 W heater is about 12.5 A).
• Forgetting the rest of the year. Annualize on cold days actually used, not 365, or you will overstate the yearly figure.
• Using an average rate instead of your own. Heating cost is so rate-sensitive that a wrong rate can flip the space-heater-vs-central decision.

Avoid these and you will know precisely what your heater costs — and whether it is the smart way to stay warm.