LED Replacement Calculator
Find out how much money you save annually by switching from incandescent or CFL bulbs to LED lighting. Useful when planning a lighting upgrade or evaluating payback period.
Last updated: September 2026
Formula below · 2 sources (nfpa.org, Wikipedia) · Updated Sep 2026
Compare with similar
About this calculator
An LED that gives the same light (lumens) as your old bulb uses far less power. Light output of the old bulb = old watts × its efficacy (lumens per watt): about 14 lm/W for incandescent (a 60 W bulb gives about 800 lumens), about 18 lm/W for halogen and about 55 lm/W for CFL. The equivalent LED wattage = those lumens ÷ the LED efficacy (80–120 lm/W). The power saved is old watts − LED watts = old watts × (1 − old efficacy / LED efficacy). Annual Savings ($) = old watts × (1 − old lm/W ÷ LED lm/W) × hours/day × 365 × rate / 1000, where dividing by 1,000 converts watt-hours to kilowatt-hours, the unit your utility bills. Bulb prices and lifetime are not included.
How to use
Example: replacing a 60 W incandescent bulb used 5 hours a day at $0.13/kWh with a 100 lm/W LED. 1. Enter Current Bulb Wattage = 60 W. 2. Select Bulb Type = Incandescent (14 lm/W): 60 × 14 = 840 lumens. 3. Select LED Efficiency = 100 lm/W: the LED needs 840 / 100 = 8.4 W. 4. Enter Daily Usage = 5 hours and Electricity Rate = 0.13. 5. Savings = 60 × (1 − 14/100) × 5 × 365 × 0.13 / 1000 = 51.6 W × 5 × 365 × 0.13 / 1000 ≈ $12.24 per year per bulb. Replacing a 15 W CFL (55 lm/W) the same way saves 15 × 0.45 × 5 × 365 × 0.13 / 1000 ≈ $1.60 per year.
Frequently asked questions
How much energy does an LED save compared to an incandescent bulb?
A standard LED bulb uses roughly 8–10 watts to produce the same brightness as a 60-watt incandescent, representing an energy reduction of approximately 85%. Over a year of typical use (3–5 hours per day), that single bulb swap saves around 50–90 kWh. In a home with 20 bulbs, the total savings can exceed 1,000 kWh annually. At average US electricity rates near $0.13/kWh, that translates to roughly $130 per year in reduced electricity bills.
What is the payback period when switching from incandescent to LED bulbs?
The payback period is the time it takes for accumulated energy savings to cover the upfront cost of the LED bulb. A quality LED bulb typically costs $3–8, while the annual savings per bulb run $5–15 depending on usage and electricity rates. This gives a payback period of roughly 6 to 18 months. After payback, every subsequent year of use is pure savings. LEDs are also rated for 15,000–25,000 hours, meaning most won't need replacement for over a decade of normal use.
Why do CFL and incandescent bulbs use different conversion factors in LED calculations?
Each bulb type turns electricity into light with a different efficacy. Incandescent bulbs give only about 14 lumens per watt (most of the energy becomes heat), halogens about 18 lm/W, CFLs about 55 lm/W and LEDs 80–120 lm/W or more. The calculator uses these efficacies to find the LED wattage that produces the same light, so replacing an incandescent saves about 85% of its power, while replacing a CFL saves only about half.