Appliance Energy Cost Calculator
Every appliance costs money to run, and the figure follows directly from its power draw and how long you use it. Multiply the wattage by the hours used per day and divide by 1,000 to get the daily kilowatt-hours, then multiply by your electricity rate for the daily cost. This calculator scales that to monthly (30 days) and yearly (365 days) totals from the wattage, daily hours, and rate you enter. Utilities bill per kilowatt-hour, so the conversion from watt-hours by dividing by 1,000 lets the rate apply directly. Wattage, hours, and rate are all user-editable inputs so the result matches your own appliance and tariff.
Appliance cost formula
Daily kWh = watts * hours per day / 1,000
Daily cost = daily kWh * electricity rate
Monthly cost = daily cost * 30
Yearly cost = daily cost * 365
Watts times hours gives watt-hours; dividing by 1,000 converts to kilowatt-hours, which the per-kWh rate prices directly.
Energy cost context
- A kilowatt-hour is the energy a 1,000-watt device uses in one hour.
- If a label shows amps and volts, multiply them to get watts.
- Standby power adds up over a year; raise the average wattage to include it.
- The monthly figure uses 30 days; the yearly figure uses 365 days.
- The EIA publishes average US residential electricity prices per kilowatt-hour.
Appliance energy cost: frequently asked questions
How do I calculate an appliance's running cost?
Multiply the appliance wattage by the hours used per day and divide by 1,000 to get the daily kilowatt-hours. Multiply that by your electricity rate for the daily cost, then by 30 and 365 for monthly and yearly figures. This calculator does all of those steps from the wattage, hours, and rate you enter.
Where do I find an appliance's wattage?
Most appliances list their power draw on a rating label or in the manual, in watts. If only amps and volts are given, multiply them to get watts. For variable-power devices, use a typical running wattage. The wattage is a user-editable input.
What is a kilowatt-hour?
A kilowatt-hour (kWh) is the energy used by a 1,000-watt appliance running for one hour. Utilities bill electricity per kilowatt-hour, so converting watt-hours to kilowatt-hours by dividing by 1,000 lets you multiply directly by the per-kWh rate to get cost.
Does standby power matter?
Yes. Many devices draw a small standby load whenever plugged in, which adds up over a year. To include it, raise the average wattage or the daily hours to reflect standby use. This calculator uses the average power and hours you supply.
Why use 30 days for the month?
The monthly figure uses 30 days as a convenient average; actual months range from 28 to 31 days. The yearly figure uses 365 days. If you need an exact month, scale the daily cost by the number of days in that month.
Official sources
- U.S. Energy Information Administration: average electricity prices.
- U.S. Department of Energy: Energy Saver guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.