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.
Formula
Cost = Watts ÷ 1000 × Hours × Rate
Example
A 1,000 W heater for 3 hours a day at 17¢/kWh: 3 kWh/day = $0.51/day ≈ $15.52/month.
Assumptions & limitations
- Results are rounded for display.
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.