Estimate an appliance’s energy use and cost per day, 30 days and 365 days from watts, hours and your rate.
Enter values, then calculate.
How the calculation works
Enter average power in watts, daily operating hours from 0 to 24, and cost per kilowatt-hour. Energy per day = watts ÷ 1,000 × hours. Cost = kWh × rate. The longer-period estimates assume the same daily usage for exactly 30 and 365 days. Use average measured power where possible; a nameplate may show maximum power.
Example and verification
1,000 W for 2 hours per day at 0.20 per kWh uses 2 kWh and costs 0.40 daily, 12.00 for 30 days and 146.00 for 365 days. Zero hours or zero rate correctly gives zero cost.
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Scope and limitations
A single constant rate is supported. Tiered tariffs, peak/off-peak pricing, taxes, standing charges and multiple appliances are excluded. Cycling devices such as refrigerators may draw power intermittently, so rated watts × all-day hours can overestimate use. This is not a utility bill forecast.
Common questions
Why are watts and kWh different?
Watts describe power at an instant. kWh describes energy accumulated over operating time.
Technical references
Related calculators
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Maintained by GadgetsFocus. Updated 2 October 2026 with AI-assisted writing and translation review; no human native-speaker or clinical review is claimed.