Electrical reference tools · No account
Kilowatt-hour Calculator
Calculate energy in kWh from W or kW, running time in hours or minutes, quantity and repeated days.
Formula and units
Energy (kWh) = watts / 1,000 × hours per day × quantity × days.
How to use these results
Enter the time each item runs per day. Use at most 24 hours or 1,440 minutes per day. Minutes are converted to hours. Quantity and repeated days are whole numbers. Constant power is assumed; duty cycles and changing loads need measured average power. No tariff is needed for this energy-only tool.
Verify critical electrical work with a qualified professional and applicable manufacturer instructions.
Worked example
1,500 W running for 2 hours uses 3 kWh. Two identical items for 30 days use 180 kWh.
Reference
Formula background: Virginia Tech — Estimating energy costs. The assumptions and input validation above define this calculator’s scope.
