Calculators
Electricity Cost Calculator
Estimate electricity energy use and cost from device wattage, daily hours, days, and rate locally in your browser.
Enter the device power in watts, the hours it runs each day, the number of days, and your electricity rate per kilowatt-hour to see the energy used and the estimated cost. The calculation runs locally in your browser; your values are not uploaded or stored.
Find an electricity cost without uploading anything.
Enter the device power in watts, the hours it runs each day, the number of days, and your electricity rate per kilowatt-hour to see the energy used and the estimated cost. Everything runs locally in your browser, so your values are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does the electricity cost calculator show?
Enter the device power in watts, the hours it runs each day, the number of days, and your electricity rate per kilowatt-hour. The calculator returns the energy used in kilowatt-hours and the estimated cost. For example, a 100 W device running 5 hours a day for 30 days uses 15 kWh, which at $0.15 per kWh costs $2.25.
Which formula does the electricity cost calculator use?
It uses energy (kWh) = watts divided by 1000 times hours per day times number of days, then estimated cost = energy in kWh times the rate per kWh. Hours per day must be greater than zero through 24.
Which inputs are accepted?
Enter device watts greater than zero through 1000000, hours per day greater than zero through 24, days greater than zero through 1000000, and a rate from 0 to 1000000 per kWh. Decimal values are accepted. Missing values, non-numeric text, and values outside these ranges show a clear error instead of a result.
Do my numbers stay private?
Yes. The calculation and copy action run locally in your browser. CodeASystem does not upload or store the values you enter.