Electric Blanket vs Space Heater Cost Calculator
Why Compare Electric Blankets with Space Heaters?
When the temperature drops, many people plug in a portable space heater to warm an entire room. Others reach for an electric blanket that directly warms the body. Both approaches offer comfort but consume electricity differently and have distinct lifespans.
This calculator quantifies the usage point where the personal warmth of a blanket becomes more economical than heating air with a fan-driven heater. It combines purchase price, expected lifespan, and energy usage into a single model. The output shows how many hours of use per season are needed before an electric blanket becomes cheaper to own and operate than a space heater.
Space heaters typically draw around 1,000–1,500 watts and can heat a small room quickly, yet they waste energy when the goal is simply to keep one person cozy. Electric blankets use a fraction of that power, often around 50–150 watts, but they have their own purchase cost and eventually wear out. Few people calculate whether frequent heater usage justifies buying a blanket instead; this tool helps you make that comparison objectively.
How the Cost Model Works
The calculator compares the per-season cost of using an electric blanket versus a space heater. Each device’s seasonal cost has two parts:
- Annualized purchase cost (device price spread over its expected lifespan in seasons)
- Electricity cost for the hours you use it in one season
Definitions used in the formulas:
- B = blanket purchase cost ($)
- Bl = blanket lifespan (seasons)
- Bw = blanket power draw (watts)
- H = heater purchase cost ($)
- Hl = heater lifespan (seasons)
- Hw = heater power draw (watts)
- R = electricity rate ($ per kWh)
- t = hours of use per season
The per-season cost for each device is:
- Blanket: purchase per season + energy per season
- Heater: purchase per season + energy per season
Written mathematically:
The break-even point is where these seasonal costs are equal.
Deriving the Break-Even Hours Formula
To find the number of hours per season where both options cost the same, set the costs equal and solve for t:
B / B_l + (B_w / 1000) × R × t = H / H_l + (H_w / 1000) × R × t
Rearranging terms gives the break-even hours per season:
t = (H / H_l − B / B_l) ÷ ( (H_w − B_w) / 1000 × R )
In simplified form:
t = (H / H_l − B / B_l) × 1000 ÷ ( (H_w − B_w) × R )
If the denominator is zero or negative (that is, the blanket uses the same or more power than the heater, or your rate is zero), there is no cost-saving break-even point based on energy savings alone. In that case, the calculator should indicate that the blanket cannot recoup its cost through lower electricity use.
Worked Example
Consider this example:
- Blanket cost: $60
- Blanket lifespan: 5 seasons
- Blanket power: 100 W
- Heater cost: $40
- Heater lifespan: 8 seasons
- Heater power: 1,500 W
- Electricity rate: $0.15 per kWh
Annualized purchase cost per season:
- Blanket: $60 / 5 = $12 per season
- Heater: $40 / 8 = $5 per season
Energy cost per hour:
- Blanket: (100 / 1000) × $0.15 = $0.015 per hour
- Heater: (1500 / 1000) × $0.15 = $0.225 per hour
The example break-even is roughly 46 hours per season: below that, the heater is cheaper overall; above that threshold, the blanket becomes the more economical choice despite its higher purchase cost.
Scenario Comparison Table
The table below illustrates how total seasonal cost changes with different hours of use, using the example values above.
| Hours per season | Blanket total cost | Heater total cost |
|---|---|---|
| 20 | $12 + (20 × $0.015) = $12.30 | $5 + (20 × $0.225) = $9.50 |
| 40 | $12 + (40 × $0.015) = $12.60 | $5 + (40 × $0.225) = $14.00 |
| 80 | $12 + (80 × $0.015) = $13.20 | $5 + (80 × $0.225) = $23.00 |
| 160 | $12 + (160 × $0.015) = $14.40 | $5 + (160 × $0.225) = $41.00 |
At low usage (around 20 hours per season), the heater is cheaper overall because its lower purchase cost dominates. As hours increase, the heater’s much higher power draw makes its energy cost rise quickly. Beyond the break-even point, the blanket’s efficiency more than offsets its higher initial price, and it remains cheaper for heavier use.
Interpreting Your Results
The calculator returns a number of hours per season. You can interpret this as follows:
- Break-even hours per season: If you expect to use supplemental electric heat more than this many hours each season, an electric blanket is likely cheaper over its life, assuming both devices give you similar comfort.
- Far below break-even: If your expected use is well below the break-even hours, a space heater may be more cost-effective, especially if you only use it occasionally.
- Far above break-even: If you routinely exceed the break-even hours, shifting more of your heating to an efficient blanket can significantly reduce your seasonal electricity costs.
Remember that the result is an estimate intended to help compare options on a consistent basis, not a precise prediction of your future energy bill.
When a Blanket Makes More Sense vs. a Heater
Cost is only one factor. Typical real-world scenarios include:
- Better suited to an electric blanket: a single sleeper, a couple who only needs localized warmth in bed, or someone who wants to stay warm while sitting in one spot (for example, at a desk or on the couch) without heating the entire room.
- Better suited to a space heater: warming a whole small room, accommodating multiple people, or quickly taking the chill off a space such as a home office or bathroom.
If you are unsure of the exact wattage for your devices, you can use typical ranges as a starting point:
- Many personal electric blankets: roughly 50–150 W
- Many portable space heaters: roughly 1,000–1,500 W
For the most accurate results, check the device label or manual for its rated wattage and your utility bill for your current electricity rate.
Assumptions and Limitations
This calculator uses a simplified model. Keep these assumptions and limitations in mind when you interpret the results:
- Constant power draw: It assumes each device draws its rated wattage continuously while in use. In reality, thermostats and built-in controls may cycle power on and off.
- Similar comfort level: It assumes that one hour of blanket use and one hour of heater use provide roughly comparable comfort for you. Some users may feel warmer or cooler with one device versus the other.
- Stable electricity rate: It uses a single electricity price and does not model time-of-use pricing or future rate changes.
- Device lifespan estimates: Lifespans are user-supplied estimates and may not match actual wear, damage, or manufacturer warranties.
- Room and home factors ignored: Insulation quality, room size, ambient temperature, and how close you sit to the heater or blanket can all affect comfort and real energy use but are not modeled here.
- Cost comparison only: The tool compares device operating cost and purchase cost. It does not address safety guidelines, whole-home heating strategy, or local regulations. Always follow manufacturer instructions and safety recommendations when using any heating device.
Because of these simplifications, your actual costs may differ from the calculator’s estimates, but the tool is useful for understanding the general trade-off between low-power localized heating (blanket) and higher-power room heating (space heater).
Using This Tool in Your Decision
To make the most of this calculator, try a few different scenarios: optimistic and conservative lifespans, higher and lower usage hours, and a range of electricity rates if your utility prices fluctuate. If the blanket looks cheaper across realistic scenarios and matches your comfort and safety needs, it is likely a good cost-saving choice. If results are mixed or close, you may prioritize other factors such as comfort, safety features, or the need to warm more than one person or room.