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Electricity Cost Calculator

Estimate the electricity used by a constant electrical load and its cost over a day, a 30-day month, a year or your own period.

Your inputs

All fields are required. Prefilled values are an editable example, not local price or usage recommendations.

No exchange rates or conversion. Enter electricity prices in the selected currency per kWh, not in cents or pence. Changing currency clears the result.

Power drawn from the supply, not cooling or heating output. Select W or kW above.

Average daily hours drawing the entered power, from 0 to 24.

Enter major currency units per kWh: for example, 0.20 means 20 cents or pence, not 20.

Whole days, 0–366. The period result uses this value; monthly and annual comparisons use 30 and 365 days.

Your estimate

Energy & running cost

Review the example inputs, enter your local electricity price, then calculate. Results clear when inputs change so an old estimate is never shown for new values.

How do I calculate electricity cost from watts and hours?

Energy (kWh) = electrical input (kW) × hours per day × days. Cost = energy × electricity price per kWh. Divide watts by 1,000 to get kilowatts.

Worked example

A 1,000 W load used 4 hours daily at 0.20 currency units/kWh uses 4 kWh and costs 0.80 per day. Over 30 days it uses 120 kWh and costs 24.00; over 365 days it costs 292.00.

Example amounts use whichever currency you select; they are arithmetic illustrations, not quoted local rates.

Assumptions & limitations

  • Assumes constant power and the same average usage every day. A kW is a rate of energy use; a kWh is an amount of energy.
  • Uses one flat electricity price. Standing charges, tiered or time-of-use tariffs, taxes and demand charges are excluded unless already included in your entered rate.

Further reading