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Power & Electrical

kWh Usage Calculator

Estimate energy usage from watts, hours and number of days.

Actual usage depends on duty cycle, thermostat behaviour and real load draw.

Notes and next steps

How it works

Estimate energy use in kWh from power and running time.

Formula used: kWh = watts ÷ 1000 × hours × days.

Worked example

500 W for 6 hours a day for 30 days is 90 kWh.

Common mistakes
  • Assuming full power all the time.
  • Mixing watts and kilowatts.
  • Forgetting duty cycles and timers.
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