A light bulb typically costs less than 1 cent to about 10 cents per day to run, depending on wattage, hours of use, and the electric rate. An LED used for eight hours often costs about 1 cent daily, while an incandescent bulb can cost several times more.
| Item | Low | Average | High | Notes |
|---|---|---|---|---|
| LED bulb, daily electricity | $0.003 | $0.01 | $0.04 | 8-12 watts; 4-12 hours daily |
| CFL bulb, daily electricity | $0.01 | $0.03 | $0.08 | 13-18 watts; 4-12 hours daily |
| Incandescent bulb, daily electricity | $0.04 | $0.10 | $0.30 | 60 watts; 4-12 hours daily |
| LED bulb, monthly electricity | $0.09 | $0.30 | $1.20 | Daily cost multiplied by 30 |
Daily cost for common home light bulbs
For one bulb, daily electricity cost is calculated by multiplying watts by hours used, dividing by 1,000, then multiplying by the electricity price per kilowatt-hour. At 16 cents per kWh, a 9-watt LED used eight hours costs about 1.2 cents daily, or roughly 36 cents per month.
At typical use, one LED costs pennies per day, not dollars. The table assumes household electricity rates of about 12-25 cents per kWh, with the average estimate using 16 cents. The bulb’s purchase price is separate from its daily operating cost.
Assumptions: One bulb, no dimmer losses, and electricity rates of $0.12-$0.25 per kWh.
What parts of a light’s daily bill add up
Electricity use accounts for nearly all recurring cost for a basic bulb. Fixtures with multiple bulbs, smart controls, or transformers can add small amounts of standby or conversion use, but the bulb wattage and operating hours usually matter most.
| Cost component | Low | Average | High | How it applies |
|---|---|---|---|---|
| LED electricity | $0.003/day | $0.01/day | $0.04/day | 8-12 watts, 4-12 hours |
| CFL electricity | $0.01/day | $0.03/day | $0.08/day | 13-18 watts, 4-12 hours |
| Incandescent electricity | $0.04/day | $0.10/day | $0.30/day | 60 watts, 4-12 hours |
| Bulb replacement allowance | $0.001/day | $0.01/day | $0.04/day | Purchase cost spread over expected life |
is the basic electricity calculation. A $5 LED lasting 15,000 hours has a replacement allowance near $0.0003 per hour, though actual life depends on use and conditions.
Wattage and hours shift the bill most
Usage time can change daily expense more than the bulb’s location. A 9-watt LED running four hours at 16 cents per kWh costs about half a cent per day; at 12 hours it costs about 1.7 cents. A 60-watt incandescent under the same conditions costs about 3.8 cents and 11.5 cents, respectively.
Every extra hour adds cost in proportion to the bulb’s wattage. A 100-watt bulb uses over 11 times the electricity of a 9-watt LED in the same fixture and for the same duration. For multiple bulbs, calculate each bulb separately and add the daily totals.
How utility rates change the price by location
Residential electricity prices vary substantially across the United States. A household paying 12 cents per kWh will spend 25% less to run a bulb than one paying 16 cents, while a 25-cent rate makes the same usage about 56% more expensive. State averages and individual utility plans differ, so a bill’s energy charge is the better input than a national estimate.
For an 8-watt LED used eight hours, the daily cost is about $0.008 at 12 cents per kWh, $0.010 at 16 cents, and $0.016 at 25 cents. Fixed monthly service charges generally do not change when one bulb is switched on, so they are not included in this per-light calculation.
LED, CFL, and incandescent daily prices compared
At eight hours a day and 16 cents per kWh, a 9-watt LED costs about $0.01 daily, a 15-watt CFL about $0.02, and a 60-watt incandescent about $0.08. Actual models vary, so the wattage printed on the bulb or package gives the closest estimate.
Replacing an incandescent with an LED can cut the bulb’s electricity use by roughly 85%. A CFL uses more power than a comparable LED, but typically much less than an incandescent. Purchase prices also differ, so a full comparison should account for replacement frequency as well as daily electricity.
Three usage examples for a realistic light budget
A 9-watt LED in a bedroom, used five hours daily at 16 cents per kWh, costs about $0.007 per day, or around $0.21 monthly. A 10-watt porch LED left on 12 hours daily costs about $0.019 per day, or $0.58 monthly.
A 60-watt incandescent in a living room, used six hours daily at 20 cents per kWh, costs about $0.072 per day, or $2.16 monthly. The examples cover electricity only and assume a steady rate; taxes, fees, or time-of-use pricing can change the bill.
When multiple bulbs make daily lighting expensive
Whole-room or whole-house use can add up even when each LED is inexpensive. Ten 9-watt bulbs used six hours daily at 16 cents per kWh cost about $0.086 per day, or $2.59 per month. Ten 60-watt incandescent bulbs under the same conditions cost about $0.58 daily, or $17.28 monthly.
High-output shop lights, outdoor floodlights, and fixtures with several bulbs should be calculated by total wattage. For example, four 15-watt bulbs count as 60 watts, even if they are controlled by one switch.
Lower the light bill by controlling wattage and runtime
Choosing an LED with suitable brightness, switching off lights in unused rooms, and using timers for outdoor fixtures reduce daily use without requiring complicated changes. Check lumens when comparing brightness; choosing only by wattage can result in a bulb that is too dim or brighter than needed.
For savings estimates, compare total fixture watts and actual hours rather than the number of switches. A dimmer may reduce consumption when compatible with the bulb, but savings depend on the dimming level and device. Smart bulbs can also draw a small standby load, so they are not automatically cheaper when left connected.