Electricity cost
Enter the appliance watts, how many hours a day it runs, how many days, and what you pay per kilowatt-hour.
- Watts to kWh
- Free, no sign-up
Free to use, no account. More everyday tools
How to use it
- Find the watts on the device or its supply.
- Enter hours per day and the number of days.
- Enter your price per kWh.
The formula
Kilowatt-hours are watts divided by 1000, times hours per day, times days. Cost is that energy times the price. A 60 watt bulb for 5 hours a day over 30 days is 9 kWh.
Standby time, a thermostat that cycles, and a tariff that changes by hour are not modelled. Use the average watts if the device is not on fully the whole time.
Private by design
Privacy
The numbers stay in this tab and are not uploaded.
Questions
Where do I read watts?
On the label, the power brick, or the manual. A current in amps times the voltage is a rough watt figure.
Is this my whole electric bill?
No. It is one load for the hours you entered.
What if the price is per unit and a unit is a kWh?
Type that price. In many bills a unit is one kWh.