Translate appliance power into the energy units on your electricity bill. The calculation is direct when power is constant; for cycling appliances, measured average power gives a better estimate than maximum rated wattage. Enter your own energy tariff rather than treating the example price as a local rate.
How to use
- Enter electrical input watts or a measured average power.
- Set daily operating hours and the number of operating days in a typical month.
- Enter your price per kWh and review both energy and cost totals.
How the calculation works
kWh = watts ÷ 1,000 × hours. Cost = kWh × price per kWh. The selected monthly schedule is repeated across 12 months for the annual projection.
Example
A 1,000 W appliance used for 2 hours on 30 days consumes 60 kWh per month. At $0.20/kWh, that is $12 per month and $144 for 12 equivalent months.
Factors affecting the result
- Nameplate power may be a maximum, especially for compressors and thermostatically controlled heaters.
- Fixed service charges and demand charges are outside this energy-only estimate.
- Time-of-use tariffs require separate calculations for each price period.
Frequently asked questions
What is the difference between kW and kWh?
kW measures the rate of electricity use. kWh measures accumulated energy. A 2 kW appliance running for half an hour uses 1 kWh.
Can I calculate standby consumption?
Yes. Enter standby watts and the number of standby hours. Calculate active operation separately if its power differs.
Sources & methodology
Calculation basis: Physics-based calculation. Methodology
- Measuring electricity — U.S. Energy Information Administration
- Energy Saver: Tips on Saving Money and Energy in Your Home — U.S. Department of Energy
Last updated: September 15, 2026