How to calculate electricity cost
Cost = Watts ÷ 1000 × Hours × Rate
Worked example. Cost per month: $15.52.
Example inputs — Power use: 1,000 watts; Hours used per day: 3; Electricity rate: 17 ¢ / kWh. Starting values are illustrative.
From George Guju, founder of Calculyn · Educational calculator guidance, not professional advice.
How it works
Watts ÷ 1,000 × hours gives kilowatt-hours (kWh), the unit on your bill. Multiply by your rate to get the cost. Check your bill for your exact rate.
Assumptions & limitations
- Results are rounded for display.
Formula and assumptions reviewed October 2026 by the Calculyn team. How we build our calculators
Frequently asked questions
Where do I find an appliance's wattage?
Look at the label on the back or bottom, or in the manual. Actual use is often lower than the maximum rating.