Holiday lights are a small part of your bill, but the gap between LED and incandescent strings is large. Here is how to work it out.
How much does it cost to run Christmas lights?
Multiply the watts by the hours on and the nights, divide by 1,000 to get kilowatt-hours, then multiply by your price per kWh. The U.S. average residential price for July 2026 was 18.31 cents per kWh, according to the Energy Information Administration. Your own bill has your rate.
How many watts is a string of Christmas lights?
The Department of Energy's niche lighting report estimates 0.4 watts per incandescent mini lamp and 0.04 watts per LED mini lamp. For a 100-lamp string that is about 40 watts versus 4 watts. That report uses 2003 data and larger C7 and C9 bulbs use more, so check the label on your package.
LED vs incandescent Christmas lights cost: a worked example
Twelve 40-watt strings on for 6 hours a night over 40 nights use 12 x 40 x 6 x 40 / 1,000 = 115.2 kWh, or $21.09 at 18.31 cents. Twelve 4-watt LED strings use 11.52 kWh and cost $2.11, so you save about $19. Energy.gov puts it another way: lighting a 6-foot tree for 12 hours a day for 40 days costs about $0.27 with LEDs versus about $10 with incandescent lights, and LED strands use about 70% less energy.
Christmas lights kWh per night
One 40-watt incandescent string running 6 hours uses 0.24 kWh a night, about 4.4 cents. A 4-watt LED string uses 0.024 kWh, less than half a cent. The savings multiply with the number of strings, which is why large outdoor displays are where the choice matters most.
Try the Christmas lights cost calculator → Related: electricity cost calculator.
Sources: U.S. Department of Energy, Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications (2003); Energy.gov, How Do Holiday Lights Work?; EIA Electric Power Monthly Table 5.6.A (July 2026 data). Verified October 9, 2026.