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Calculation details
Energy-cost estimate only. Verify your utility tariff, taxes, time-of-use pricing, equipment efficiency, and manufacturer specifications before relying on the result.
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What does this calculator estimate?
Estimate how much you save by switching to LED bulbs. Enter the existing bulb wattage, LED wattage, number of bulbs, hours used per day, electricity rate, and LED purchase cost to get annual savings and simple payback — entirely in your browser.
- Annual savings = watts saved × bulbs × hours × 365 ÷ 1000 × rate.
- A 9 W LED replaces a 60 W incandescent (≈800 lumens).
- LEDs use 75–85% less energy than incandescents and last far longer.
Choosing the right LED wattage
LED wattage is not a 1:1 match for incandescent wattage — LEDs produce far more light per watt. As rough equivalents: a 5–7 W LED matches a 40 W incandescent, 9–10 W matches 60 W, 13–15 W matches 100 W, and a 15–18 W LED is a good stand-in for a 150 W incandescent. Use the lumen rating on the package for a precise match, since brightness is what matters.
Where LED savings matter most
The savings scale with how long and how often a bulb is on. Lights used several hours a day — kitchen, living room, outdoor fixtures that run at night — pay back fastest. A bulb used 30 minutes a day saves much less and may not justify the higher LED price on energy alone, though its longer life still helps.
Why the payback period is a helpful number
Simple payback divides the LED purchase cost by the annual energy savings. It tells you how many years of energy savings repay the upfront price. It excludes lamp life, dimmer compatibility, rebates, and maintenance, so treat it as a first-order check rather than a complete cost-of-ownership model.
How this calculator works
Formula
Annual savings = count x (old watts - new watts) x daily hours x 365 / 1000 x rate; payback = upgrade cost / annual savings.
Worked example
Twelve 60 W bulbs replaced with 9 W LEDs, 5 hours a day at $0.17/kWh: 1,116.9 kWh saved, $189.87 a year, a $48 upgrade pays back in 0.25 years.
Assumptions to verify
- Savings assume the bulbs run the entered hours every day of the year.
- Lamp life, dimmer compatibility, rebates, and maintenance savings are excluded.
- Nameplate watts may differ from actual draw; LED drivers use a small standby amount.
Frequently asked questions
How much does an LED bulb save per year?
A 9 W LED replacing a 60 W incandescent used 5 hours/day at $0.17/kWh saves about $15.80 per bulb per year (60−9 W = 51 W saved). With 12 bulbs that is roughly $190 a year, before accounting for the longer lamp life of LEDs.
What LED wattage replaces a 60 W bulb?
A 9–10 W LED roughly matches the light output of a 60 W incandescent (about 800 lumens). For a 100 W incandescent use a 13–15 W LED, and for a 40 W incandescent a 5–7 W LED. This calculator applies your exact wattage pair.
Are LEDs really worth switching to?
Usually yes for bulbs used several hours a day: they use 75–85% less energy and last far longer, so the higher purchase price is recovered in energy savings and avoided replacements. The calculator shows both annual savings and simple payback for your specific numbers.
Does an LED's savings depend on the electricity rate?
Yes — the higher your rate, the faster the payback. At $0.10/kWh the same 12-bulb swap saves about $112 a year; at $0.30/kWh it saves about $335. Enter your local rate for an accurate figure.
Cite this tool
BoringToolsKit. “LED Savings Calculator.” boringtoolskit.com/led-savings-calculator/ (reviewed August 2026). Free to reference in articles, syllabi, and answer posts with a link.
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