Compare electric blanket and space heater electricity costs using your wattage, nightly schedule, thermostat on-time, and electricity rate.
Table of contents
How to use our Electric Blanket vs Space Heater Cost Calculator
- Enter the label value for Electric blanket wattage and Space heater wattage at the heat settings you use.
- Enter separate schedules in Blanket use per night and Heater use per night; they do not need to match.
- Enter your bill's usage-based Electricity rate. Include charges that change with kWh, but leave out fixed account charges.
- Open Advanced options if needed. Set Heater thermostat on-time below 100% only if you have a reasonable estimate of how often the heater actively heats.
- Check Lower electricity-cost choice and the monthly costs. A positive Estimated monthly electricity savings with blanket means the blanket costs less under your entered schedule.
Definitions
Watt (W): A measure of power, or how fast a device uses electricity while operating.
Kilowatt-hour (kWh): The energy unit used on electric bills. A 1,000 W device running for one hour uses 1 kWh.
Electricity rate ($/kWh): The usage-based price paid for each kWh of electricity.
Heater thermostat on-time: The percent of scheduled heater time when its heating element is actively drawing its rated wattage.
Use night: One night when the entered blanket and heater schedules apply.
Heating season: The user-chosen number of weeks used to estimate seasonal electricity cost.
Common mistakes and quick fixes
Mistake: Entering 1.5 in Space heater wattage because the heater is rated 1,500 W.
Fix: Enter 1,500 W. The calculator converts watts to kilowatts during the calculation.
Mistake: Using the same number for Blanket use per night and Heater use per night when the heater runs only before bed.
Fix: Enter each device's real schedule separately.
Mistake: Setting Heater thermostat on-time to 40% without a measurement or solid estimate.
Fix: Use 100% when unsure, or use a smart plug record to estimate active heating time.
Mistake: Including a fixed customer charge in Electricity rate.
Fix: Use supply and delivery charges that vary with kWh. Fixed account charges usually do not change with device use.
Mistake: Reading a negative Estimated monthly electricity savings with blanket as an error.
Fix: A negative value means the space heater costs less under the schedules and thermostat on-time you entered.
Mistake: Treating Lower electricity-cost choice as a comfort comparison.
Fix: Remember that an electric blanket warms a person or bed, while a space heater warms room air.
Limitations & Key Assumptions / Boundary Conditions
- The estimate uses label wattage. Actual power can differ by heat setting, thermostat behavior, blanket zone use, and product design.
- The Heater thermostat on-time percentage is an estimate unless measured. Use 100% if the heater may heat for its full scheduled time.
- Electricity rates can vary by time of day, tier, season, taxes, and utility plan. A single Electricity rate is a planning estimate.
- Fixed customer or account charges are excluded because they usually do not change when either device is used.
- The calculation compares electricity charges only. It excludes purchase price, repairs, lifespan, and any effect on central heating use.
- An electric blanket warms a person or bed, while a space heater warms room air. Lower electricity cost does not mean equal warmth or room temperature.
- For a dual-zone blanket, enter the wattage for the zones you expect to use, not automatically the maximum for both sides.
Methodology
Energy and cost calculation
The calculator changes watts into kilowatts, multiplies by each device's nightly hours, then multiplies by the electricity rate. The heater calculation also applies Heater thermostat on-time.
blanket night kWh = (Electric blanket wattage / 1000) x Blanket use per night
heater night kWh = (Space heater wattage / 1000) x Heater use per night x (Heater thermostat on-time / 100)
nightly cost = nightly kWh x Electricity rate
The monthly estimate uses an average of 52 weeks divided by 12 months, rather than assuming every month has exactly four weeks.
monthly use nights = Nights used per week x 52 / 12
monthly device cost = nightly device cost x monthly use nights
heating-season device cost = nightly device cost x Nights used per week x Heating season
electricity savings with blanket = space heater cost - electric blanket cost
How to read savings
A positive savings value means the blanket has the lower estimated electricity cost. A negative value means the heater has the lower estimated cost for the values entered. The lower-cost choice compares unrounded monthly costs, so it can still choose one device when displayed costs look equal after rounding to cents.
Worked example
With a 100 W blanket used 8 hours per night, the blanket uses 0.8 kWh per use night. A 1,500 W heater used 3 hours per night with 40% thermostat on-time uses 1.8 kWh. At $0.1811 per kWh, their nightly costs are about $0.14 and $0.33. Used 7 nights per week, the monthly savings with the blanket is about $5.49.
Calculation choices
The default electricity rate is an editable US residential planning value from EIA monthly electricity price data [1]. Fixed account charges are left out because this comparison estimates the change in usage-based electricity charges. The calculation does not assume that the blanket and heater provide equal comfort or heat the same space.