LED Savings Calculator
Estimate the yearly energy and money you save by replacing halogen or incandescent fittings with LEDs, and optionally the payback period on the upgrade.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the number of fittings, the old wattage per fitting and the new LED wattage per fitting.
- Enter the hours per day the lights run and the days per year (default 365), plus your electricity price in $/kWh.
- Optionally add the total upgrade cost to see the payback period in years.
How it works
Annual energy saved (kWh) = number of fittings × (old watts − new watts) ÷ 1000 × hours per day × days per year. Annual cost saving = that energy × your electricity price. If you enter the upgrade cost, payback (years) = cost ÷ annual saving. The tool also shows the old and new annual energy use for comparison.
Worked example
Worked example. Swapping 20 × 60 W halogens for 20 × 10 W LEDs running 10 hours a day, 365 days a year, saves 20 × 50/1000 × 10 × 365 = 3,650 kWh a year. At $0.30/kWh that is $1,095.00 a year; an $800 upgrade pays back in about 0.73 years.
Common mistakes
- Entering total watts for all fittings instead of the wattage per single fitting — the tool multiplies by the number of fittings for you.
- Using purchase watts for the LED that are higher than or equal to the old lamp — LEDs should draw far fewer watts for the same brightness.
- Forgetting that longer LED life also cuts replacement-lamp and labour costs, which this running-cost figure does not include.
Frequently asked questions
Why must the new wattage be lower than the old?
The saving comes from the drop in power draw. If the new LED wattage is equal to or higher than the old lamp there is no energy saving, so the calculator asks for a lower LED wattage.
Does this include the cost of buying the LEDs?
Only if you enter the total upgrade cost — then it shows a simple payback period. The energy and dollar savings themselves are the ongoing running-cost savings and don't subtract the purchase price.
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Tip: Enter any known values to calculate the remaining results.
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