At the U.S. average price of 18.16¢ per kWh. Your state's price changes these numbers; use the calculator.
Work out your cost
Change any number. The price per kWh is on your electric bill.
Starts at the U.S. average residential price, 18.16¢/kWh (August 2026, EIA, checked Oct 24, 2026). Month is 30 days; year is 12 such months.
The formula
cost = watts × hours ÷ 1,000 × price per kWh
Worked example: 1,500 W × 8 h ÷ 1,000 = 12 kWh a day. 12 kWh × $0.1816 = $2.18 a day, or about $65.38 over 30 days.
How many watts does a space heater vs central heat use?
Most are rated 900 to 1,500 W. The exact figure is on the label on the back or bottom.
- Most U.S. plug-in space heaters top out at 1,500 W on high, because a standard 120 V / 15 A household circuit can only safely carry about that much. CPSC staff testing found even a heater advertised as 2,000 W measured a maximum input of 1,500 W.
- Typical two-setting ceramic heaters are 900 W on low and 1,500 W on high (e.g. Lasko 754200: 900 W / 1,500 W).
- DOE lists electric resistance heating (space heaters, baseboards, electric furnaces) as essentially 100% efficient at the point of use: every kWh of electricity becomes a kWh of heat. A heat pump moves heat instead of making it, and DOE says it can cut heating electricity by about 50% compared with electric furnaces or baseboards.
- Central electric furnaces are much larger loads. Nordyne's E2EB 15 kW model draws 15.4 kW with its blower (about 10 times a 1,500 W space heater). Gas and oil furnaces are billed in fuel, not kWh; DOE rates them by AFUE, so a space heater vs gas comparison depends on your gas price and the furnace efficiency, not on a single U.S. average dollar figure.
Cost at different electricity prices
| Use | Nevada (lowest state)12.72¢/kWh | U.S. average18.16¢/kWh | New York28.65¢/kWh | California29.75¢/kWh | Hawaii (highest state)47.18¢/kWh |
|---|---|---|---|---|---|
| High (1,500 W), 4 h/day (evening supplement, thermostat set back)180 kWh a month | $22.90$275/yr | $32.69$392/yr | $51.57$619/yr | $53.55$643/yr | $84.92$1,019/yr |
| High (1,500 W), 8 h/day (one occupied room)360 kWh a month | $45.79$550/yr | $65.38$785/yr | $103$1,238/yr | $107$1,285/yr | $170$2,038/yr |
| Low (900 W), 8 h/day (one room, low setting)216 kWh a month | $27.48$330/yr | $39.23$471/yr | $61.88$743/yr | $64.26$771/yr | $102$1,223/yr |
| High (1,500 W), 12 h/day (long evening and overnight wake hours)540 kWh a month | $68.69$824/yr | $98.06$1,177/yr | $155$1,857/yr | $161$1,928/yr | $255$3,057/yr |
| High (1,500 W), 24 h/day (running both systems; avoid)1,080 kWh a month | $137$1,649/yr | $196$2,354/yr | $309$3,713/yr | $321$3,856/yr | $510$6,115/yr |
Per month (30 days) and per year (12 such months). Real use is usually seasonal. Average residential prices for August 2026 from the same EIA table. Your utility's rate, including delivery charges, may differ. Check the price per kWh on your bill.
Ways to pay less
- Turn the central thermostat down when you heat one room DOE says you can save as much as 10% a year on heating and cooling by setting the thermostat back 7 to 10°F for 8 hours a day. That is the condition under which a space heater can beat central heat: the whole-house system runs less, and you pay the heater's $0.27 an hour only for the room you use.
- Do not run the space heater on top of normal central heat Leaving the thermostat alone and plugging in a 1,500 W heater just adds about $65 a month at 8 hours a day. The heater does not make the furnace or heat pump cheaper; it adds a second load.
- Close the door and treat it as zone heat DOE's electric resistance heating guidance notes that heating only occupied rooms (zone heating) can save more than 20% compared with heating the whole house. Close the door, block drafts, and let the heater's thermostat cycle off once the room is warm.
- If your central system is a heat pump, lean on it first DOE says heat pumps can provide up to three times more heat than the electricity they use, and can cut heating electricity by about 50% versus electric furnaces or baseboards. A 3-ton heat pump at about 2.9 kW (~$0.53 an hour in our heat pump page's example) usually beats a resistance space heater for whole-house comfort. Save the plug-in heater for a cold corner, not as the main heat.
- On gas or oil heat, compare fuel cost, not just the heater's $0.27 DOE rates gas and oil furnaces by AFUE (annual fuel utilization efficiency). A high-AFUE furnace turns most of each unit of fuel into heat for the whole house. A space heater can still win for a single room if you set the thermostat back, but running both means you buy gas or oil and electricity at once.
Safety. Plug space heaters directly into a wall outlet, never an extension cord or power strip, and keep them at least 3 feet from beds, curtains, and furniture. CPSC advises against leaving a heater running unattended or while you sleep.
Questions
Is it cheaper to run a space heater or central heat?
Only if the space heater lets you turn central heat down. A 1,500 W heater costs about $0.27 an hour at 18.16¢/kWh. A 15 kW electric furnace with blower costs about $2.80 an hour while the elements run. Heat one room with the heater and set the thermostat back 7 to 10°F (DOE's setback range), and the heater can be the cheaper plan. Leave central heat on its normal schedule and add the heater, and the bill goes up by the heater's full cost (about $65 a month at 8 hours a day).
How much does a space heater cost per hour compared with an electric furnace?
About $0.27 an hour for 1,500 W on high, or $0.16 on low (900 W), at 18.16¢/kWh. Nordyne's 15 kW E2EB furnace draws 15.4 kW with its blower, about $2.80 an hour, roughly ten times the space heater. The furnace heats the whole house through ducts; the space heater heats one room.
How much does it cost to run a space heater instead of central heat for a month?
At 8 hours a day on high, about $65.38 a month ($32.69 at 4 hours, $98.06 at 12 hours) at the U.S. average rate. That replaces central heat only if the thermostat is set back so the furnace or heat pump barely runs. For comparison, a 15 kW electric furnace with 4 hours of element run time a day is about $336 a month on its own.
Is a space heater cheaper than a gas furnace?
It can be for one room if you turn the gas furnace thermostat down and stop heating unused space. DOE measures gas furnace efficiency with AFUE, and notes that electric resistance heat is often more expensive than other fuel options for whole-house heating. There is no single U.S. average dollar-per-hour for gas that matches the EIA electricity figure, so compare your therm price and AFUE on the bill against the space heater's $0.27 an hour, and count only the hours you actually run each one.
Is a heat pump cheaper to run than a space heater?
For the same amount of heat, usually yes. DOE says heat pumps can cut heating electricity by about 50% compared with electric resistance heat. On our heat pump page, a 3-ton unit drawing 2.9 kW costs about $0.53 an hour and delivers several times the heat of a 1,500 W space heater. Use a space heater as a spot warmer with the heat pump setback rules for heat pumps (DOE warns against manual setbacks that trigger backup resistance strips).
Is a bitcoin heater cheaper than a space heater for the same room?
Per kWh of heat, somewhat, once you count mining income. Both turn electricity into heat roughly one to one, but a heater miner earns bitcoin while it runs. At the November 6, 2026 hashprice, an 800 W Avalon Mini 3 earns back about 35% of its electricity at 18.16¢/kWh, so its heat costs the equivalent of about 11.82¢ per kWh against 18.16¢ for a plain space heater. The same zone-heating rule still applies: turn the central thermostat down. A heat pump still beats both on cost per unit of whole-house heat. Mining income moves with the bitcoin price and network difficulty; our bitcoin heater page recalculates it daily.
Sources
- U.S. EIA: Electric Power Monthly, Table 5.6.A: Average price of electricity by state, August 2026 (released Oct 23, 2026). Used for: U.S. average residential rate (18.16¢/kWh) and state rates
- U.S. DOE: Energy Saver Guide (2022). Used for: Up to 10% a year from a 7 to 10°F thermostat setback for 8 hours a day; heat pumps up to 3× heat per kWh and ~50% less electricity vs electric furnaces/baseboards; AFUE for furnaces and boilers; electric heat often costlier than other fuels for whole-house heating
- U.S. DOE Energy Saver: Electric resistance heating (archived copy, January 16, 2026; the energy.gov page now returns 404). Used for: Electric resistance ~100% efficient at point of use; space heaters as a room resistance option; zone heating can save more than 20% vs heating the whole house; electric furnaces cost more than room resistance because of duct losses and blower power
- U.S. CPSC: Staff Assessment on Portable Electric Heaters (Feb 2023). Used for: Heater advertised as 2,000 W measured 1,500 W max input; UL 1278 context
- U.S. CPSC: Space heater, furnace and fireplace safety warning. Used for: 3-foot clearance, wall outlet only, don't run while sleeping (HTTP 403 to automated clients; cited from prior WattCost pages and public CPSC release title)
- Lasko 754200 ceramic heater, manufacturer specifications. Used for: Typical settings: 900 W low / 1,500 W high
- Nordyne: E2EB-xxx-HB series electric furnaces, technical specifications. Used for: 15 kW model total input 15.4 kW with blower for central electric heat comparison
- WattCost: hashprice (mempool.space and CoinGecko), November 6, 2026, and Canaan Avalon Mini 3 specifications. Used for: Avalon Mini 3: 37.5 TH/s at 800 W; mining income at $32.45 per PH/s a day