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GNW / Free calculator
Electricity Cost Calculator
Use average power draw and your own electricity rate to estimate operating cost.
Enter your values and choose Calculate.
Estimates only. Values are calculated in your browser and are not sent or saved by this tool.
The calculation
Energy in kWh = watts ÷ 1,000 × hours used × days. Estimated cost = kWh × your electricity rate. A 100 W device used 8 hours a day for 30 days consumes 24 kWh; at $0.15/kWh, the energy charge is $3.60.
Which wattage should I enter?
Use measured average consumption where possible. A charger or power supply’s rated maximum is not necessarily the device’s average draw. Variable loads, standby use, fixed charges, taxes and time-varying tariffs can change the actual bill. USD is the display currency; no currency conversion is performed.