The LED Equivalence Table
LED bulbs draw roughly 85% less powerfor the same brightness: a 60 W incandescent becomes a 9 W LED, a 100 W becomes 15 W. Because brightness varies slightly by product, the presets in the calculator are the typical center of the range — copy the “replaces XX W” line from the LED box you are holding for the exact math.
Where the Savings Actually Come From
Two streams, and the second one surprises people. Electricity: a 60 → 9 W swap on a 3-hour-a-day bulb saves about 55 kWh — $9+ a year at the US average rate. Replacement bulbs: incandescents die at ~1,000 hours, so a 3-hour daily bulb needs a new one every year; LEDs are rated 15,000–25,000 hours, which at the same usage is one purchase per 15–20 years. The calculator prices both, which is why the payback on a $2.50 LED usually lands under three months.
Frequently Asked Questions
How much does it cost to leave a 60-watt bulb on all day?
A 60W incandescent burning 24 hours uses 1.44 kWh — about $0.24/day and $89/year at the US average rate of $0.17/kWh. The 9W LED equivalent costs about $13/year for the same around-the-clock use. The difference per bulb is why always-on fixtures (porch, hallway) are the first place to convert.
Do LED bulbs really last 25,000 hours?
Quality LEDs are rated 15,000–25,000 hours, and at 3 hours a day that rating equals 14–23 years of service. Real life is shorter in enclosed fixtures and hot rooms — heat is the main LED killer — so buy bulbs marked 'suitable for enclosed fixtures' for those spots. Even at half the rated life, you replace an incandescent roughly annually and an LED once a decade.
Is switching to LED worth it if I already have CFLs?
Much less. A 60W-equivalent CFL draws about 13–15W versus 9W for an LED, so the savings are a few dollars a year per bulb — plus LEDs light instantly and contain no mercury. The practical advice: leave working CFLs alone and buy LEDs when they burn out, but convert any incandescent or halogen bulb today.