Calculate electricity usage

Estimate appliance kilowatt-hours and 30-day cost from measured watts, daily run time, and a tariff.

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ToolElectricity Usage Calculator
Input
Output
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Preview

How it works

Watts multiplied by hours and divided by 1,000 gives daily kilowatt-hours. Multiplying by 30 gives the comparison month, and multiplying again by price per kilowatt-hour gives cost.

Formula
daily kWh = watts × hours per day ÷ 1,000
  • No tariff is assumed because unit prices, taxes, and time bands vary.
  • The monthly figure always represents 30 days rather than the current calendar month.

Worked example

Calculate electricity usage
Input
											Appliances: Fridge, 150, 8
Laptop, 65, 6
Price per kwh: 0.3
Output
												Name    Daily kwh  Monthly kwh  Monthly cost
------  ---------  -----------  ------------
Fridge  1.2        36           10.8
Laptop  0.39       11.7         3.51

When to use this

Households price plug-meter readings, offices compare equipment loads, and tenants approximate one appliance’s contribution to a bill.

Edge cases

  • A cycling refrigerator needs average power or duty-cycle hours rather than nameplate watts multiplied by 24.
  • An appliance name containing a comma breaks the three-column line format.
  • Standby consumption and time-of-use prices need separate rows or calculations because one wattage and one tariff cannot express them.

References