LED Savings Calculator
Enter the wattage of the bulbs you are replacing, the wattage of the LED replacements, how many bulbs you have, and how long they run each day. The calculator shows your annual electricity savings, the payback period for the upfront LED cost, cumulative savings over time, and how much CO2 you keep off the grid each year.
Formula
Worked example
Ten 60 W incandescents replaced by 8 W LEDs, running 5 hrs/day for 7 days/week at $0.16/kWh: annual hours = 5 x 365.25 = 1,826 hrs; kWh saved = (60-8)/1,000 x 1,826 x 10 = 949 kWh; annual savings = 949 x $0.16 = $151.87; upfront cost for 10 LEDs at $5 each = $50; payback = $50 / ($151.87/12) = about 4 months.
How switching to LED saves money
LED (light-emitting diode) bulbs convert a far higher fraction of electrical energy into visible light than incandescent or halogen bulbs, which waste the majority of their energy as heat. A standard 60 W incandescent bulb can be replaced by an 8-9 W LED that produces the same amount of light (around 800 lumens). That is roughly an 85% reduction in energy use per bulb. Multiply that saving across every fixture in a home and the kilowatt-hours add up quickly, cutting both the electricity bill and the carbon footprint of the household.
Understanding the payback period
LED bulbs cost more upfront than incandescents or halogens, but they more than recover that cost through lower electricity bills and far fewer replacements. A typical incandescent lasts around 1,000 hours; a quality LED is rated for 15,000-25,000 hours, so you may never replace it for the life of the fixture. The payback period this calculator reports is the number of months before your combined electricity savings and avoided bulb-replacement costs fully cover the initial LED purchase price. For high-use fixtures running 5 or more hours per day, payback periods of 3-6 months are common.
CO2 and environmental impact
Electricity generation in the US produces an average of about 0.855 lbs of CO2 per kWh (EPA eGRID 2023 national average). Every kilowatt-hour of electricity your LEDs save is therefore a kilowatt-hour that does not need to be generated at a power plant. For a home with 20 bulbs switched from incandescent to LED at typical US usage, the annual CO2 reduction is often equivalent to removing a small car from the road for a month or more. The figure this calculator shows is a national average; your actual impact depends on your local utility mix.
Tips for getting the most from LEDs
Match lumens, not watts, when choosing a replacement: look for the lumen output on the packaging rather than comparing wattage, since LEDs achieve the same brightness at a fraction of the power. For fixtures used only a few minutes at a time, such as closets or bathrooms, payback takes longer because the power savings are smaller, but the extended lifespan benefit still applies. Dimmer compatibility matters: not all LEDs are dimmable, so check the packaging if you use dimmer switches. Color temperature (measured in Kelvin) affects the feel of a room: 2,700 K is a warm white close to incandescent, while 4,000-5,000 K is a cooler, more neutral white suited to kitchens and workspaces.
Equivalent wattages by bulb type
| Incandescent (W) | Halogen (W) | CFL (W) | LED (W) | Lumens |
|---|---|---|---|---|
| 100 | 80 | 23 | 14 | 1600 |
| 75 | 60 | 19 | 10 | 1100 |
| 60 | 48 | 14 | 8 | 800 |
| 40 | 32 | 10 | 6 | 450 |
| 25 | 20 | 7 | 4 | 250 |
Approximate equivalent wattages that produce the same light output (lumens). Use this to choose the right LED replacement.
Frequently asked questions
How do I find the right LED wattage to replace my current bulb?
Match by lumens (light output), not watts. A 60 W incandescent produces about 800 lumens; look for an LED labeled 800 lm, which will typically be 8-9 W. The reference table on this page shows approximate equivalents for common incandescent wattages.
Why is the payback period so short for high-use bulbs?
The more hours a bulb runs, the more electricity it uses, so the bigger the saving per month when you switch to LED. A bulb running 8 hours per day saves roughly twice as much per month as one running 4 hours per day. High-use fixtures like kitchen lights or living-room lamps typically pay back their LED cost in a few months.
Do LED bulbs save money if the electricity rate is low?
Yes, but payback takes longer. If your rate is $0.08/kWh (half the US average), annual savings per bulb will be roughly half the amount shown at $0.16/kWh. The LED still saves money over its lifetime, it just takes more months before the upfront cost is recovered.
What electricity rate should I enter?
Find your electricity rate on your monthly utility bill, usually listed as cents per kWh or dollars per kWh on the usage or rate section. The US residential average in 2024 was about 16 cents per kWh ($0.16), but rates range from under 10 cents in some states to over 30 cents in Hawaii and parts of the Northeast.
Does this calculator account for replacing bulbs over time?
Yes. The net savings figure and the year-by-year chart include the cost of purchasing LED replacements when they eventually burn out over your projection horizon, as well as the incandescent or halogen replacement bulbs you no longer need to buy. The LED lifetime input determines how many LED replacements are needed over the period.
How much CO2 do LEDs actually save?
The CO2 figure uses the US EPA eGRID 2023 national average of 0.855 lbs of CO2 per kWh generated. Your local grid mix may be cleaner (more renewables) or dirtier (more coal) than the national average, so treat this as an order-of-magnitude estimate. In carbon-intensive grids the CO2 savings are even larger; in grids with high renewable penetration they are smaller but the cost savings are the same.