Calculate cost from average watts
Convert watts to kilowatts, multiply by hours, then multiply by the price per kWh. For a hypothetical 50 W average used six hours, energy is 0.05 × 6 = 0.30 kWh. At $0.18/kWh, one night costs $0.054 and 30 nights cost $1.62.
This is an arithmetic example, not a typical rating for every blanket. Size, controller setting, warm-up time and cycling can change average power. Do not multiply the highest label wattage by the whole night and call it measured use unless the product actually stays at that input.
Compare preheating with overnight use
Suppose the same example averages 80 W for a 30-minute preheat and 40 W for the next 5.5 hours. Energy is 0.08 × 0.5 + 0.04 × 5.5 = 0.26 kWh, costing about 4.7 cents at $0.18/kWh. Separating the phases shows which assumption matters.
If the controller has several heat levels, record the setting and duration. A plug-in meter that is electrically suitable for the product can total kWh over several nights; follow both manuals and do not place the meter or cord where it can be pinched.
For seasonal planning, multiply the measured nightly figure by the nights you realistically expect to use it. Keep the electricity rate visible beside the result. That makes it easy to update the estimate after a tariff change without repeating the measurement or presenting an old price as current.
Compare warmth options without equating them
An electric blanket warms the user, while a space heater warms room air. Their costs do not prove that they provide the same comfort or suit the same situation. Compare the outcome you need first, then calculate each suitable option with its own average watts and hours.
For a fair budget, include only the hours you expect to use. A low nightly amount can still grow across a long season, while a high-power appliance used briefly may cost less than a simple wattage comparison suggests.
Check the product before using it
The CPSC electrical safety checklist says to inspect electric blankets for damaged wiring, plugs, connectors, charred areas or fraying, and warns against folding or pinching heat-producing wires during use. Follow the exact product instructions and current recall information.
Cost calculations never justify using a damaged or recalled product. Keep the model information, care label and controller together, and stop using equipment that shows damage or behaves abnormally.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.