Hong Life CalculatorsUnderstanding the electric blanket running cost calculator — concept and principle
This calculator estimates the electricity cost of an electric blanket or heated mattress pad from its power rating, daily hours of use, the electricity price and the number of days per month. It is useful for comparing a blanket with space heating, setting a winter budget, or deciding whether to pre-heat the bed instead of running the blanket all night.
How it is calculated
- kWh per month = power (W) ÷ 1,000 × hours per day × days per month.
- Monthly cost = kWh per month × price per kWh.
- Yearly cost = monthly cost × 12.
Use the rated wattage on the blanket's label or controller; dual-control models may list the power for each side.
The principle
Energy equals power times time, so a 100 W blanket running for 10 hours uses 1 kWh. An electric blanket is a resistance heater: virtually all the electricity becomes heat, and because that heat goes directly into the bed under insulating covers, a small amount of power keeps you warm. That is why blankets are much cheaper to run than heating a whole room. Most controllers switch the heating wire on and off to hold the chosen setting, so the average power over a night is usually lower than the rating, often around 30–60% of it.
Worked example
- Inputs: 100 W, 8 hours a day, 0.25 per kWh, 30 days (USD).
- Energy per day: 100 ÷ 1,000 × 8 = 0.8 kWh.
- Per month: 0.8 × 30 = 24 kWh.
- Monthly cost: 24 × 0.25 = $6.00.
- Yearly cost: 6 × 12 = $72.00.
| Power (W) | Monthly cost |
|---|---|
| 25 | $1.50 |
| 50 | $3.00 |
| 75 | $4.50 |
| 100 | $6.00 |
| 125 | $7.50 |
| 150 | $9.00 |
| 200 | $12.00 |
How to read the result
The figure is an upper limit at full power. At a typical 30–60% duty cycle the same use would cost roughly $1.80–$3.60 a month. The yearly cost assumes year-round use; for winter only, multiply by the actual months. For comparison, a 2,000 W space heater running 8 hours uses 16 kWh a day, as much as the blanket uses in about 20 days at full power.
Common mistakes
- Assuming the blanket draws its full rating all night.
- Counting both sides of a dual blanket once when both are on.
- Applying the yearly figure to a heater used only in winter.
Frequently asked questions
Is it cheaper to pre-heat the bed?
Yes. Running the blanket for 30–60 minutes before bed and switching it off or to low uses far less energy than heating all night.
Does a higher setting cost more?
Yes; the controller keeps the heater on for a larger share of the time.
How does a water-heated mattress pad compare?
It heats and circulates water, so it works differently; enter its own rated wattage and compare it the same way.
Sources: U.S. Department of Energy, Energy Saver: Estimating Appliance and Home Electronic Energy Use · IEC 60335-2-17, Particular requirements for blankets, pads, clothing and similar flexible heating appliances