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A rated wattage is a scenario, not necessarily typical use. Measure a complete, representative period when possible.
How to measure electricity useFree energy tools
Appliance electricity cost calculator
Use your own numbers to estimate an appliance’s electricity cost. No account needed.
Your appliance & usage
Estimated monthly cost
$25.92
for the usage entered
Per day$0.86
Per year · 4 months of use$103.68
Monthly electricity use144 kWh
Estimates cover this appliance’s electricity use, excluding fixed account charges. They are not a forecast of your whole bill.
Put the estimate to work
Your next useful step
These guides explain options; no purchase is required to use your estimate.
How the estimate works
In measured-energy mode: average watts = observed kWh ÷ observation hours × 1,000. The projection applies that continuous-period average across 24 hours daily. Include idle time in the observation; do not enter a single cycle and assume it repeats all day. Monthly kWh = observed kWh ÷ observation hours × 24 × days. Zero energy is valid; a zero observation period is not.
Monthly kWh = watts ÷ 1,000 × hours/day × days/month
Monthly cost = monthly kWh × rate
Annual cost = monthly cost × months used
For an air conditioner or dehumidifier, nameplate watts can overstate typical use because the compressor cycles or changes speed. Enter average power measured over a representative period. If you only have rated power, treat the result as a constant-power scenario.
A month is the number of days you enter, not a calendar prediction. Twelve months of 31 days is a 372-day scenario; use a representative monthly average for annual planning.
Read our calculation methodology