Worked example: Electricity Calculator
Appliance use. This fixed reference example shows one complete scenario; the interactive results above use your current inputs.
View the example inputs
- Appliance power
- 1000 W
- Use per day
- 3 hours
- Number of days
- 30 days
- Energy price
- 0.2 currency/kWh
| Calculated quantity | Example result |
|---|---|
| Energy used | 90 kWh |
| Energy cost | 18 currency |
Using a simplified electrical model
Keep electrical quantities and circuit assumptions distinct
Voltage, current, resistance, power and energy use different units. Power is a rate of energy use; a watt-hour is an energy quantity. A DC resistive relationship does not automatically describe an AC load with reactance or a non-unit power factor.
A voltage-drop estimate needs conductor length, cross section and resistivity at the relevant temperature. A one-way length can require a round-trip circuit factor. A quoted energy tariff also needs a defined cost per energy unit rather than only a currency amount.
Check what the model leaves out
Real installations can depend on starting current, heating, terminal losses, protective devices, installation method and local rules. The calculator includes only the quantities and assumptions named on this page.
Use it to inspect the arithmetic and compare entered scenarios. It does not certify ampacity, wiring safety, component selection or code compliance. Product and installation requirements must be checked separately.
Formula and calculation method
kWh=watts/1000×hours/day×days. Cost=kWh×unit price. Excludes fixed charges, taxes, time-of-use and tiered tariffs unless included in the entered rate.
Reference Sources
Frequently asked questions
How does this calculator work?
kWh=watts/1000×hours/day×days. Cost=kWh×unit price. Excludes fixed charges, taxes, time-of-use and tiered tariffs unless included in the entered rate.
What assumptions should I check?
Check the units and definitions shown beside each input. Results use the values you enter.
Can I save or print this calculation?
Use Copy link with inputs to reproduce the scenario, Download results for a text record, or Print. Where a schedule is shown, its CSV download includes every row.