How Much Does It Cost to Run an LED Light Bulb?

The answer to how much it costs to run a light bulb today is almost always an LED answer, and it is a very small number. A standard LED that replaces a 60 W incandescent produces about 800 lumens on 8 to 10 W. At the 9 W default for 5 hours a day, it uses 0.045 kWh, under one cent a day and about $2.84 a year at the national average rate. A 100 W equivalent LED draws about 13 to 16 W and a 40 W equivalent about 5 to 6 W, so you can scale the result from the wattage on the base.

The comparison that matters is against the incandescent bulb it replaced. A 60 W incandescent on the same 5 hour schedule uses 0.3 kWh a day, about $18.94 a year, so each LED swap saves about $16 a year. Multiply that by the 20 to 40 sockets in a typical house and lighting goes from a real line on the bill to a minor one. LEDs also last 15,000 to 25,000 hours against about 1,000 for an incandescent, so you buy far fewer bulbs.

Turning lights off when you leave a room is still worth it with LEDs, just in smaller amounts. There is no start-up surge that makes switching cost more than leaving them on, and frequent switching does not meaningfully shorten an LED's life. A bulb left on all night by mistake costs about a cent.

Smart bulbs add one wrinkle. A Wi-Fi or Zigbee smart bulb stays connected while switched off in the app, typically drawing 0.2 to 0.5 W in standby. Across a dozen smart bulbs that is a few kWh a year, still small, but it means a smart bulb switched off in the app is never fully off. If a lamp is controlled by a wall switch, the standby draw ends when the switch is off.