LED Light Bulb Savings Calculator

How to use this calculator

Enter how many bulbs you're replacing, what type they are, how many hours a day they're on, your electricity rate, and what you'll pay per LED bulb. Bulbs you use the most, like kitchen and living room fixtures, save the most, so it's worth running those separately from closets and guest rooms.

How this is calculated

Each bulb saves the difference in watts between the old bulb and a 60 W-equivalent LED (about 9 W), times hours on per day, times 365. The calculator converts that to kilowatt-hours and multiplies by your electricity rate. Payback is the cost of the LED bulbs divided by the annual savings.

Bulb wattages

For the same light output (about 750–800 lumens), a standard incandescent draws 60 W, a halogen 43 W, a spiral CFL 13 W, and an LED 8–9 W, based on manufacturer spec sheets. Replacing incandescent or halogen bulbs pays back fast; replacing working CFLs saves only a few watts each, so it usually makes more sense to switch them as they burn out.

Example

Replacing 20 incandescent bulbs used 3 hours a day saves about 1,117 kWh a year. At $0.17/kWh that's about $190 a year, so $40 of LED bulbs pays back in about 3 months. The same 20 bulbs replacing CFLs save about $15 a year and take about 2.7 years to pay back.

Estimate only, based on energy use. It doesn't count the replacement bulbs you no longer need to buy: an incandescent lasts about 1,000 hours, while a typical LED is rated for 15,000 hours or more.