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Energy & water

LED savings and payback calculator

Compare two power levels at the same usage and estimate when the extra purchase cost is recovered.

Free & no registration Calculated in your browser
01

Your inputs

The starting values are an example.

Decimals: 12.5 · Thousands: 1,234.56. Follow the field instructions for lists.

02

Your result

Enter your values and select Calculate.

Your calculation will appear here.

Your result will include the relevant values and units.

Understand the calculation

Formula and example

How it is calculated

Saved kWh per year = (old watts − new watts) / 1,000 × daily hours × 365

Worked example

Replacing 60 W with 9 W for four hours daily saves 74.46 kWh per year, or €26.06 at €0.35/kWh.

Things to check

  • Compare lights with suitable brightness and light quality. Lifespan and replacement costs are not modelled.
  • Use one currency consistently. Examples use euros; the calculation works with any currency.