Calculate how much it costs to run a space heater per hour, day, month, or year. Enter wattage, usage hours, and electricity rate.
Space heaters are one of the most energy-hungry appliances in any home. A typical portable electric heater runs at 1,500 watts — the maximum for a standard 15-amp outlet in the US. Running that heater for 8 hours costs $1.20–$1.80 per day depending on your electricity rate, which can add $35–$55 to your monthly bill.
Despite this, space heaters can be cost-effective when used strategically. Heating a single room with a space heater while lowering the central thermostat by 5–10 degrees can save money overall, since you're only heating the space you're actually using. The key is understanding the true running cost.
This calculator shows you the hourly, daily, monthly, and annual cost of running any electric space heater. Whether you have a ceramic, oil-filled, infrared, or fan-forced heater, the math is the same: watts times hours divided by 1,000 times your rate.
Precise measurement of this value supports sustainable energy planning and helps organizations reduce their environmental impact while maintaining operational performance and comfort levels.
Space heaters can either save or waste money depending on how you use them. This calculator reveals the exact cost so you can make informed decisions about zone heating vs central heating. Regular monitoring of this value helps energy teams detect usage anomalies early and address equipment malfunctions or operational issues before they drive utility costs higher.
Cost = Watts × Hours / 1,000 × Rate ($/kWh)
Result: $1.68/day
A 1,500W space heater running 8 hours per day uses 1,500 × 8 / 1,000 = 12 kWh. At $0.14/kWh, the daily cost is 12 × $0.14 = $1.68. Over a 30-day month, that's $50.40.
Most portable space heaters have two settings: 750W (low) and 1,500W (high). The high setting is designed for a 15-amp circuit and draws the maximum safe continuous load. Some heaters offer 500W, 1,000W, or 1,500W settings for more flexibility.
The most cost-effective way to use a space heater is "zone heating": heat only the room you're in while lowering your central thermostat by 5–10°F. This strategy works best in large homes where central heating wastes energy on unoccupied rooms. The savings depend on your home size, insulation, and climate.
An electric space heater produces 1 unit of heat per unit of electricity (COP = 1.0). A heat pump produces 2–4 units of heat per unit of electricity (COP = 2–4). If you're supplementing heat frequently, a ductless mini-split heat pump may be more economical despite the higher upfront cost.
At 1,500 watts and $0.14/kWh, a space heater costs about $0.21 per hour. On the low (750W) setting, it costs about $0.105 per hour. Your actual cost depends on your specific electricity rate.
It depends. If you're heating one or two rooms in a large house, a space heater plus lowering the thermostat can save money. But running multiple space heaters to heat an entire home is almost always more expensive than central heating.
All electric space heaters convert electricity to heat at nearly 100% efficiency, so the "type" matters less than you might think. The difference is in heat distribution: oil-filled radiators provide steady warmth, ceramic heaters heat quickly, and infrared heaters warm objects directly.
Yes. Running a 1,500W heater 8 hours/day for 30 days adds about 360 kWh to your monthly usage, costing $40–$60 at typical rates. That can increase a $120 monthly bill by 30–50%.
Modern space heaters with tip-over protection and overheat shutoff are relatively safe, but fire safety experts generally recommend turning them off when sleeping or leaving the room. Never drape anything over a heater or place it near flammable materials.
1,500 watts is the maximum load for a standard US 15-amp, 120-volt outlet (15A × 120V = 1,800W, with 80% continuous load = 1,440W, rounded to 1,500W). This is a safety limit set by electrical code, not a manufacturer choice.