Free energy calculator
Appliance Electricity Cost Calculator
Estimate the cost of operating an appliance over a chosen number of days. Use your own bill rate for a decision-relevant result.
Calculate your estimate
Change the example values to match your system.
Estimated result
Ideal—
Typical—
Conservative—
These are estimates, not guaranteed performance.
Formula and method
Energy (kWh) = watts × hours per day × days ÷ 1,000. Cost = energy × price per kWh.
Percent fields are entered as percentages; the calculation converts them to decimal fractions. Displayed results are rounded to two decimal places.
What the inputs mean
- Appliance power (W)
- Enter appliance power in W.
- Use per day (hours)
- Enter use per day in hours.
- Number of days (days)
- Enter number of days in days.
- Electricity price ($ / kWh)
- Enter electricity price in $ / kWh.
Worked example
A 1,000 W appliance used 2 hours daily for 30 days consumes 60 kWh and costs $9.60 at $0.16/kWh.
Why the real result may differ
- Temperature, battery age, wiring resistance, and changing loads can move actual results away from the estimate.
- Manufacturer ratings may be measured under different test conditions. Measure the load when practical.
Common mistakes
- Do not confuse watts (power) with watt-hours (energy).
- Do not enter a percentage as a whole number: 90% is entered as 90 in this form and converted internally.
Frequently asked questions
Is this result guaranteed?
No. It is an engineering estimate; equipment, temperature, age, and duty cycle affect real performance.
Why are three estimates shown?
The ideal case ignores practical losses, while typical and conservative cases apply the efficiency and margin entered above.
Related tools
References
Last reviewed: August 6, 2026