Electricity Usage and Cost Calculator
Estimate electricity use over repeated daily operating hours and calculate cost using a stated tariff.
How to use this calculator
- Enter average watts, operating hours per day, number of days and price per kWh.
- Confirm that all inputs use the stated units and the same population, period or scope.
- Change one assumption at a time when comparing scenarios.
Formula used by the electricity usage cost calculator
kWh = W ÷ 1000 × hours/day × days
- kWh = W ÷ 1000 × hours/day × days
- Assumes average power and tariff remain constant; standing losses and extra bill fees may not be included.
- Inputs are validated against required ranges and outputs are rounded for readability.
Worked examples
Worked example
A 150 W device runs five hours daily for 30 days at 0.30 per kWh.
Energy use is 22.5 kWh and the energy cost is 6.75.
Energy use is 22.5 kWh and the energy cost is 6.75.
Understanding the result
Estimate electricity use over repeated daily operating hours and calculate cost using a stated tariff.
Assumes average power and tariff remain constant; standing losses and extra bill fees may not be included.
Important notes
Assumes average power and tariff remain constant; standing losses and extra bill fees may not be included.
Use the result as a calculation aid for the inputs supplied; confirm critical specifications independently.
Frequently asked questions
Should I enter rated power or measured power?
Measured average power is usually more representative when available.
Does this equal the full electricity bill?
No; it estimates the entered device energy only.
How do I use this calculator?
Enter average watts, operating hours per day, number of days and price per kWh.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.