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Appliance Energy Use & Running Cost Calculator

Estimate recurring electricity use and cost from power, daily operating time and an energy tariff.

  • Formula & worked example
  • Private in your browser
  • No signup
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Edit a calculated value to solve backwards, or lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

An appliance drawing 2 kW for 3 hours per day uses 6 kWh per day. At 0.20 per kWh, that is 1.20 per day or 438.30 over the model’s 365.25-day year.

Energy = average operating power × operating time; energy cost = energy × price per kWh

Worked example

Enter these known values and leave the other values blank.

Average operating power
2 kW
Energy price
0.2 USD / kWh
Usage time
3 hrs / days
Energy used
6 kWh / days
Cost
438.3 USD / yrs

Assumptions and limitations

  • Power and energy are different: kW measures operating power; kWh measures energy over time.
  • The same operating schedule repeats throughout the selected period.

Common questions

Why might this differ from my electricity bill?

The estimate uses constant average power and one energy price. Thermostats, duty cycles, standby use, tiered or time-dependent tariffs, fixed charges and taxes can change the bill. Use measured average power and your applicable energy rate.

What does the yearly result mean?

The time unit uses a fixed 365.25-day year and an average month equal to one twelfth of that year. It is a recurring-rate estimate, not a dated billing calculation. Select the cost period you need.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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