What an LED bulb actually draws
A standard replacement LED draws 9 W and produces roughly 800 lumens — the same light as the 60 W incandescent it replaces. Bulbs in this class run from about 5 W for a dimmer 450-lumen bulb up to 15 W for a brighter 1,100 or 1,600-lumen equivalent. Lumens are the unit of light output; watts are the unit of electricity consumed. Those two things used to move together, which is why people learned to shop by watts, and they no longer do.
The usage assumption matters as much as the wattage. Three hours a day is the standard federal assumption used on the Lighting Facts label and in rated-life arithmetic, so it is the correct apples-to-apples basis for comparing one bulb against another. DTE's chart uses 0.008 kWh for a 60 W-equivalent LED, consistent with that. Three hours is an annual average across a whole house, not a claim about any particular fixture: a kitchen ceiling light may run six hours a day and a closet bulb six minutes.
There is no meaningful standby draw on an ordinary LED. Off is off. The exception is a smart bulb, whose wireless radio keeps drawing 0.3 to 0.5 W around the clock so the bulb can hear a command to switch on. That small permanent draw turns out to be the most interesting number on this page.
A dimmable LED on a compatible dimmer does draw proportionally less when dimmed, though not perfectly linearly.
What that costs, worked through
Watts × hours ÷ 1,000 = kWh per day. For one LED: 9 W × 3 hours = 27 watt-hours, or 0.027 kWh a day. Over a 30.4-day month that is 0.8 kWh, which at the US average rate of 18.44 cents per kWh is about 15 cents a month. For a full year: 9.85 kWh, or roughly $1.82 per bulb.
Across the range, a 5 W bulb costs about $1.01 a year and a 15 W bulb about $3.03. Running one continuously — a porch light left on 24 hours a day — is 9 W × 24 = 0.216 kWh a day, 78.8 kWh a year, about $14.53.
The comparison that pays for the bulb is with what it replaced. A 60 W incandescent at the same three hours uses 65.7 kWh a year against the LED's 9.85 kWh: a saving of 55.8 kWh, or about $10.29 a year, per bulb. Multiply by the number of sockets in a house and the LED transition is one of the few energy changes that genuinely paid for itself quickly.
At the household level, EIA's 2020 residential survey puts all home lighting at 654 kWh a year — about $120.60 at the average rate — down sharply from the incandescent era. That total is the honest frame: individual bulbs cost pennies, and lighting as a whole still costs real money. Check it against your own rate in the kWh cost calculator.
What makes the number move
Brightness and hours are the whole story for an ordinary bulb; everything else is a detail.
- Lumens. More light costs more electricity. A 1,600-lumen bulb draws roughly twice a 450-lumen one. This is the factor to think about at purchase.
- Hours in the fixture. A hallway bulb and a kitchen bulb of identical rating can differ tenfold in annual cost purely by position in the house.
- Season. Lighting hours are strongly seasonal — long dark evenings in December, long light ones in June. Do not take a winter month's lighting use and multiply it by twelve. That overstates the year badly at northern latitudes, and the three-hour federal assumption already averages across the seasons.
- Smart features. A connected bulb adds 0.3 to 0.5 W of permanent radio draw regardless of hours.
- Dimming. Genuinely reduces draw on a compatible dimmer, though the relationship is not exactly proportional.
What does not vary meaningfully is efficiency between comparable LEDs. Efficacy — lumens delivered per watt consumed — differs modestly between a budget bulb and a premium one, and it is not worth paying much extra to chase. Colour temperature, measured in kelvin, changes the character of the light and not the consumption; a 2700 K warm bulb and a 5000 K daylight bulb of the same lumen output draw the same.
Whether it is worth doing anything about
If your house is already on LEDs, the answer is essentially no. At $1.82 a year per bulb, no habit change will register — turning lights off in empty rooms is good practice and worth pennies.
Two things do deserve attention at purchase. The first: shop by lumens and colour temperature, not by watts. The watt figure now tells you only what the bulb costs to run, which is trivial; lumens tell you whether the room will be bright enough, and kelvin tells you whether the light will feel warm or clinical. Buying a "60 W equivalent" without checking lumens is how people end up with rooms that are subtly too dim.
The second, and this is the one worth arguing about: skip smart bulbs in fixtures you never control remotely. Their radios draw 0.3 to 0.5 W continuously even when the light is off, which is 2.6 to 4.4 kWh a year. In a seldom-used room — a guest bedroom, a basement, a coat closet lit fifteen minutes a day — that standby draw exceeds the bulb's own lighting consumption, which would be well under 1 kWh a year. You would be paying more to let the bulb wait for an instruction than to produce light.
Where automation is genuinely useful, put the smarts in the switch instead. One smart switch controls every bulb on the circuit with one radio, and it works with ordinary cheap LEDs. Compare it against other small always-on loads in the appliance energy cost calculator.
How it compares with everything else you plug in
One LED at 0.8 kWh a month is the second-smallest load on this site, behind only a phone charger at 0.5 kWh. It is about one-seventh of a WiFi router at 5.8 kWh, one-eleventh of a laptop at 9.1 kWh, and one-thirty-fourth of a desktop computer at 27.4 kWh.
Bulbs are not used one at a time, though, which is what makes lighting worth discussing at all. EIA's 654 kWh a year for household lighting is equivalent to about 66 LED bulbs each running three hours a day — a plausible count for a whole house once you include closets, hallways, exterior fixtures and appliance lamps. At the monthly level, 654 kWh a year is 54.5 kWh a month, which is roughly what an electric clothes dryer uses at 54.7 kWh and more than a refrigerator's 36.5 kWh.
So the honest statement is a two-parter. Any single LED is beneath notice. Household lighting in aggregate is a real line on the bill, comparable with the dryer, and it is the one category where a technology change has already removed most of the cost that used to be there.
The remaining opportunity is not in swapping LEDs for better LEDs. It is in finding the incandescent and halogen fixtures still running in the house — and in not leaving high-hour exterior lights burning all night. See the average electric bill figures for where lighting sits against the whole statement.
Frequently asked questions
How many watts does an LED bulb use?
About 9 watts for a standard bulb producing roughly 800 lumens, which is the same light output as an old 60 watt incandescent. The common range is 5 watts for a dimmer 450-lumen bulb to 15 watts for a brighter 1,100 to 1,600-lumen one. Shop by lumens rather than watts: lumens tell you how bright the room will be, while watts now only tell you the running cost, which is trivial either way. Colour temperature in kelvin changes the look of the light, not the consumption.
How much does it cost to run an LED bulb for a year?
About $1.82 per bulb at the US average rate of 18.44 cents per kWh. The arithmetic: 9 watts for the standard 3 hours a day is 0.027 kWh, which is 9.85 kWh over a year, times $0.1844. Monthly that is 0.8 kWh and about 15 cents. Left on continuously — a porch light burning 24 hours — the same bulb costs about $14.53 a year. Household lighting as a whole runs closer to 654 kWh a year, about $120.60, because a house has dozens of sockets.
Do smart bulbs use electricity when off?
Yes, 0.3 to 0.5 watts continuously, because the wireless radio has to stay awake to hear the command to switch on. That is 2.6 to 4.4 kWh a year per bulb. In a room you rarely enter, that standby draw can exceed what the bulb uses producing light — a fixture lit fifteen minutes a day consumes well under 1 kWh a year. Where you want automation, a smart switch is the better answer: one radio controls every bulb on the circuit, and you can use ordinary inexpensive LEDs behind it.
Is it worth switching the last few bulbs in my house to LED?
If the remaining bulbs are incandescent and in fixtures you use daily, yes — each 60 watt bulb replaced saves about 55.8 kWh and $10.29 a year at three hours a day, so the bulb pays for itself in months. Target the highest-hour fixtures first: kitchen, living room and porch, not the closet you open twice a week. If the last holdouts are in low-use fixtures, the saving is small enough that replacing them on failure rather than proactively is a perfectly reasonable choice.