Why the Device Cost Is the Wrong Thing to Focus On
Search for what an electric blanket costs to run and you'll find dozens of articles telling you it's about two cents an hour. That's true and almost useless, because nobody buys a blanket instead of heating their house — they buy it hoping to heat the house less.
So the real equation has two sides:
- What you save by lowering the thermostat — roughly 1% of your heating cost per °F of setback sustained over 8 hours, per Department of Energy guidance.
- What you spend running the device — usually trivial, $20–30 across a whole season for a blanket.
The asymmetry is the point. A 100W blanket costs about $22 for a 150-night season, while a 7°F overnight setback on a $1,200 heating bill saves about $84. Net: roughly $62. Bump the setback to 10°F over 10 hours and the net approaches $130.
Why a Space Heater Is a Different Animal
Personal heating devices draw 55–150 watts. A space heater draws 1,500 — roughly fifteen times more. That changes the arithmetic completely.
A space heater can still win, but only when it lets you set back the whole house substantially while heating one occupied room. Run it 8 hours a day for a 150-day season and it costs about $324 in electricity at 18¢/kWh, so you need a large setback on a large heating bill to come out ahead. If your central heat is gas — usually cheaper per delivered BTU than electric resistance — the space heater has to overcome that gap too.
Select it in the dropdown above and the calculator will show you whether it actually nets out. Our space heater cost calculator and central heat vs space heater comparison go deeper on that specific trade.
The Safety Floors Nobody Mentions
Most coverage of this topic stops at "it's cheaper." Three limits are worth knowing before you set the thermostat aggressively low:
- Around 55°F — frozen pipes. This is the usual floor recommended for an unoccupied house. Pipes in exterior walls, crawl spaces and unheated garages freeze before the thermostat's room does. If you want to know how fast your house would reach this on its own during an outage, our power outage cooling calculator works out the timeline.
- Around 60°F — condensation and mould. Warm moist air from cooking, showering and breathing condenses on cold surfaces. This is the failure mode people hit when they heat only themselves through a whole winter, and it's a genuine reason not to simply turn everything off.
- Around 64°F — general health guidance. The World Health Organization suggests this as a minimum indoor temperature, and closer to 68°F where infants, elderly or unwell people are in the home. Personal heating is a way to be comfortable at a lower setting, not a licence to go below these.
Running a bathroom or kitchen extractor fan and cracking a window briefly after showering does more for condensation risk than an extra degree on the thermostat, and costs nothing.
What Actually Makes a Lower Setting Comfortable
The device is one lever. Several others are free and matter as much:
- Draughts. Air movement across skin reads as cold regardless of air temperature. Sealing gaps around doors, windows and outlets is the highest-return comfort fix in most homes.
- Humidity. Dry air feels colder at the same temperature. Winter indoor humidity often drops below 30%; bringing it to 40–45% lets many people sit comfortably a degree or two lower. Our humidifier running cost calculator covers what that costs to run.
- Cold surfaces. You radiate heat to cold windows and uninsulated walls. Heavy curtains closed at dusk make a measurable difference to how a room feels.
- Where you actually sit. Moving a chair away from a large window is free and often worth more than a degree.
If you're weighing this against structural fixes, our insulation savings calculator compares the returns — insulation lowers your heating bill without requiring you to feel colder, which personal heating does not.