Electricity Cost Calculator
Device energy and cost estimate
Enter power, schedule, and price per kWh
Result
Calculation summary
Enter values to see the result
Energy cost preview
Power to energy to cost
Formula
cost = kW × devices × hours per day × days × price per kWh
- Cost per day
- $0.64
- Projected 30-day cost
- $19.20
- Projected 365-day cost
- $233.60
How to use this calculator
- 1Enter the rated or measured power for one device and the number of identical devices.
- 2Enter average operating hours per day and the number of days in the planning period.
- 3Enter the energy price per kilowatt-hour and calculate energy use and cost.
Formula
Cost = (watts ÷ 1000) × quantity × hours per day × days × price per kWh
Power is converted to kilowatts, multiplied by operating time to get kilowatt-hours, then multiplied by the entered energy rate.
Calculation steps
- Convert the power of one device to kilowatts.
- Multiply by the number of identical devices.
- Multiply total kilowatts by daily operating hours and days to obtain kilowatt-hours.
- Multiply energy use by the entered price per kilowatt-hour.
Worked example
A 1,000 W device running 4 hours a day for 30 days uses 120 kWh. At 0.16 per kWh, its estimated energy charge is 19.20.
Assumptions
- Entered power is treated as constant while the device is operating.
- Every entered device uses the same power and schedule.
- The rate is a flat energy price per kWh.
- Fixed charges, taxes, tiered prices, time-of-use rates, demand charges, and standby use are excluded.
Sources
Frequently asked questions
What is a kilowatt-hour?
It is an energy quantity equal to one kilowatt of power sustained for one hour.
Should I use rated or measured wattage?
Measured average wattage is usually more representative when a device cycles or varies its power.
Why can my utility bill be different?
Bills may include fixed fees, taxes, tiers, time-of-use rates, demand charges, and other adjustments not modeled here.
Does the yearly estimate use the entered number of days?
The selected-period result does. The 30-day and annual comparisons use the same daily schedule projected across 30 and 365 days.