How do you estimate appliance energy use?

Multiply power in kilowatts by actual operating hours to estimate kilowatt-hours.

Worked example

A 100 W lamp operating for 5 hours uses 0.5 kWh. Refrigerators and air conditioners cycle, so rated power multiplied by all hours may overestimate use.

Try it with your own numbers

Use the Energy Calculator to check another example. Read the input labels carefully and keep units consistent.

Before you use the answer

Choose the correct starting quantity and keep full precision until the final step. An arithmetic result describes the numbers entered; the usefulness of the result depends on accurate measurements and the assumptions in the calculation.