Using the Electricity Calculator
Power is entered in watts, time in hours per day, and the tariff as cost per kilowatt-hour. The model assumes the entered power applies throughout those operating hours. Appliances that cycle on and off may need an average-power or equivalent-runtime estimate.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- Appliance power (W)
- 1000
- Hours per day
- 4
- Days
- 30
- Cost per kWh
- 0.2
Example result
- Energy (kWh)
- 120
- Energy cost
- 24
Method and assumptions
kWh = watts / 1000 × operating hours. Excludes fixed charges, tiered tariffs and duty-cycle changes.
Distinguish a model from a circuit specification
Electrical calculations describe the assumptions entered in the form. Real components, cables and supplies also have ratings, tolerances and operating conditions. Confirm whether the model is for DC resistance, energy over time or another specific quantity. A mathematically consistent result is not by itself a complete design or installation check.
Common question
Are watts and kilowatt-hours the same thing?
No. Watts measure power at a moment, while kilowatt-hours measure energy over time. A 1,000-watt load running for one hour uses one kilowatt-hour under this constant-power model.
Guide updated .