A 1,500-watt electric space heater costs between $0.12 and $0.36 per hour to run, depending on your local electricity rate. At the 2026 U.S. national average of $0.168/kWh, that's $0.252 per hour, $2.02 per 8-hour day, or $60.48 per month running 8 hours daily. Your actual cost depends on three variables: wattage, electricity rate, and hours of use.
The formula is simple, but the devil is in the details — your state's electricity rate can make the same heater cost 3× more in one place than another.
The Electric Heater Cost Formula
Every electric heater cost calculation uses this formula:
Cost = (Watts ÷ 1,000) × Electricity Rate ($/kWh) × Hours of Use
That's it. There's no efficiency variable because all electric resistance heaters convert electricity to heat at ~100% efficiency. A cheap $30 heater and an expensive $150 heater both cost the same to run at the same wattage.
Where to find your electricity rate: Check your most recent utility bill. Look for "price per kWh" or "energy charge." It's typically listed in cents per kilowatt-hour (e.g., 16.8¢/kWh = $0.168/kWh). You can also find your state's average at the EIA's electricity data page.
Electric Heater Cost Tables
Cost by Wattage at U.S. Average Rate ($0.168/kWh)
Cost by State: How Location Changes Everything
Electricity rates vary enormously across the U.S. Running the exact same 1,500W heater for 8 hours costs $1.20 in Louisiana but $4.00+ in Massachusetts.
High-rate state alert: If you live in California, Connecticut, Massachusetts, or Hawaii, a space heater is an expensive way to heat. At $0.30+/kWh, a 1,500W heater costs over $100/month for 8 hours/day. In these states, a heat pump or gas supplemental heating is almost always a better financial choice.
How ECO Mode and Thermostats Reduce Costs
The numbers above assume continuous, full-power operation. In practice, a heater with a thermostat or ECO mode draws significantly less power because it cycles on and off.
The message is clear: a heater with ECO mode in a well-insulated room can cost nearly half of one running full blast in a drafty room.
Cost Comparisons: Space Heater vs. Other Heating Methods
Electric resistance heating (which includes all space heaters) is the most expensive common heating method per BTU. The only scenario where it's cost-effective is when you're heating a single small room while reducing central heat — the zone heating strategy.
Real-World Cost Examples
Example 1: Supplementing Central Heat in a Home Office
Setup: Amanda in Denver, CO works from home in a 150 sq ft office. She lowers the thermostat from 72°F to 64°F and runs a 1,500W oil-filled radiator with ECO mode for 8 hours.
- Electricity rate: $0.15/kWh
- Space heater (ECO mode, avg. 850W): 6.8 kWh/day × $0.15 = $1.02/day ($30.60/month)
- Gas savings from lowering thermostat 8°F: ~10% of $160 gas bill = $16/month saved
- Net cost increase: ~$14.60/month for a warm office while saving on whole-house heating
Example 2: All-Night Bedroom Heating
Setup: Carlos in Chicago has a drafty 200 sq ft bedroom. He runs a 1,500W heater for 10 hours overnight (10 PM – 8 AM) on a timer.
- Rate: $0.17/kWh
- Full-blast cost: 15 kWh × $0.17 = $2.55/night ($76.50/month)
- With thermostat + ECO (avg. 1,100W): 11 kWh × $0.17 = $1.87/night ($56.10/month)
- Winter season (5 months): $280–$382
Example 3: High-Rate State Sticker Shock
Setup: Lisa in San Jose, CA uses a 1,500W ceramic heater in her apartment for 6 hours/day.
- Rate: $0.32/kWh (PG&E Tier 2)
- Daily cost: 9 kWh × $0.32 = $2.88/day ($86.40/month)
- With a portable heat pump (COP 2.5, same 6 hours): ~3.6 kWh × $0.32 = $1.15/day ($34.56/month)
- Savings from switching to heat pump: $51.84/month ($259 per season)
Example 4: Multiple Heater Household
Setup: The Kim family in Portland, OR runs heaters in 3 rooms: a 1,500W in the living room (5 hrs), a 1,000W in a kid's bedroom (8 hrs), and a 750W in a home office (6 hrs).
- Rate: $0.12/kWh
- Living room: 7.5 kWh × $0.12 = $0.90
- Bedroom: 8 kWh × $0.12 = $0.96
- Office: 4.5 kWh × $0.12 = $0.54
- Total daily: $2.40 | Monthly: $72.00 | Winter season: $360
At $72/month for three heaters, they should compare this to their central heating cost. If gas central heat for the whole house costs $120/month, running three space heaters plus lowering the furnace may not save money.
Tips to Lower Your Electric Heater Costs
- Use ECO mode or a thermostat — saves 20–50% vs. constant full power.
- Right-size your wattage — use 750W for small rooms, 1,000W for medium, 1,500W only for large spaces.
- Set a timer — avoid running while sleeping or away. Even 2 fewer hours/day saves $15–$30/month.
- Seal the room — close doors, use draft stoppers, apply window film. A sealed room needs less heater runtime.
- Use infrared for personal heating — a 400W infrared desk heater warms you directly at 1/4 the cost of a 1,500W room heater.
- Check for time-of-use rates — some utilities charge less for overnight electricity. Pair with an oil-filled radiator for thermal storage.
- Consider a heat pump — for regular use, a $400–$700 portable heat pump cuts costs by 50–70%.
Key Takeaways:
- Formula: Cost = (Watts ÷ 1,000) × $/kWh × Hours. A 1,500W heater at $0.168/kWh = $0.25/hour.
- Monthly costs at 8 hrs/day range from $36 (Louisiana) to $155 (Hawaii) for a 1,500W heater.
- ECO mode can cut costs by 30–50% in well-insulated rooms.
- Electric resistance heating is the most expensive per BTU. It only saves money as a zone-heating supplement.
- In high-rate states ($0.25+/kWh), a portable heat pump is a much cheaper heating option.
- Always check your actual kWh rate on your utility bill — state averages may not reflect your plan.
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