How to use this calculator
- Enter your own values in the labeled fields. Check the units and assumptions before comparing results. Only the fields needed for your selected calculation mode are shown.
- Your answer updates automatically. Review the calculation steps to see exactly how it was calculated.
- Copy, share, save, or download your result. Saved inputs stay on this device.
How the calculation works
Watts describe power, while kilowatt-hours describe energy accumulated over time. The duty factor represents how much of the scheduled period the appliance runs at its entered power. Use measured average power with a 100% duty factor, or running power with an appropriate duty estimate, to avoid counting cycling twice.
A worked example
1,000 W running 2 hours daily for 30 days at 100% duty uses 60 kWh. At $0.20/kWh, cost is $12.
Reading your result
Use the main result together with its units and supporting figures. Display values are rounded; calculations keep their underlying precision. A change in inputs or assumptions can change the answer. Compare the step-by-step working with your intended use before relying on an estimate.
Frequently asked questions
Does this include fixed utility charges?
No. It uses only your entered energy rate.
What about an appliance that cycles?
Enter its running-power duty factor or measured average power, without double adjustment.
Sources & methodology
This calculator uses the mathematical identity and assumptions stated above. No current rates, prices, or external data are loaded. Conversion tools use international unit definitions.
Formula review: October 24, 2026. Read our methodology.