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.
About this calculator
LED bulbs consume significantly less electricity than incandescent or CFL equivalents while producing the same luminous output. This calculator estimates annual energy cost savings using the formula: Annual Savings ($) = (Old Watts × Conversion Factor / LED Efficiency × Hours/Day × 365 × Electricity Rate) / 1000, where the conversion factor accounts for the light output ratio of the old bulb type (incandescent: 0.85, CFL: 0.75, halogen: 0.5). Dividing by 1000 converts watt-hours to kilowatt-hours (kWh), the billing unit used by utilities. LED efficiency (lumens per watt) determines how bright an LED must be to match the old bulb. Because LEDs can produce the same lumens at a fraction of the wattage, the difference in annual kWh consumed directly translates to cost savings at your local electricity rate.
How to use
Example: Replacing a 60 W incandescent bulb with an LED, used 5 hours/day at $0.13/kWh, with LED efficiency factor 1. 1. Enter Current Bulb Wattage = 60 W. 2. Select Bulb Type = Incandescent (conversion factor 0.85). 3. Enter LED Efficiency = 1. 4. Enter Daily Usage = 5 hours. 5. Enter Electricity Rate = 0.13 $/kWh. 6. Annual cost = (60 × 0.85 / 1) × 5 × 365 × 0.13 / 1000 = 51 × 5 × 365 × 0.13 / 1000 ≈ $12.10/year saved per bulb.
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?
The conversion factor reflects how efficiently each bulb type converts electrical energy into visible light. Incandescent bulbs waste about 90% of their energy as heat, making them the least efficient — hence a conversion factor of 0.85 representing the large efficiency gap versus LEDs. CFLs are more efficient than incandescents but still lose more energy than LEDs, giving a factor of 0.75. Halogen bulbs fall between the two at 0.5. These factors normalize the comparison so the calculator correctly estimates equivalent LED wattage and the resulting energy savings.