How Much Does It Cost to Leave a Lamp On All Day? (2026)

A lamp uses whatever wattage its bulb is rated for, and almost nothing else. The base and shade do not draw power. Switching, dimming, and smart-bulb circuitry add at most a watt or two. So the running cost is the bulb cost, full stop.

The math is the same for every lamp: watts × hours ÷ 1,000 × your state rate. A 9W LED running 8 hours a day is 9 × 8 ÷ 1,000 = 0.072 kWh per day, or about 2.2 kWh a month. At the April 2026 U.S. residential average of 18.05¢/kWh from the EIA Electric Power Monthly, that is $0.39 a month. Eight hours a day across two lamps is $0.78. Run a single 9W LED 24 hours a day and you spend $1.30 a month. None of these numbers move the bill enough to notice.

Replace the LED with a 60-watt incandescent and the same lamp at 8 hours a day costs $2.60 a month. At 24/7 it is $7.80 a month, or $94.80 a year. Per lamp. That is the number that surprises most homeowners. A single forgotten incandescent left on around the clock for a year costs nearly as much as a midsize refrigerator does in the same period.

A lamp is a fixture for a bulb. Wattage depends entirely on what is screwed in. Most household lamps fit a standard E26 socket and accept anything from a 4W LED to a 150W incandescent (or a 100W CFL). Real-world ranges:

Table lamp: Typically a single 60W-equivalent bulb. A 9W LED draws 9 watts. A vintage incandescent draws 60 watts. A halogen pulls 40 to 50 watts. Bedside-table lamps often hold lower- wattage bulbs (40W incandescent or 6W LED), bringing the ranges down further.

Floor lamp: Usually rated for up to 150W in a single socket, or 3 to 5 sockets at 40W to 60W each. A modern LED floor lamp pulls 8 to 20 watts. A three-bulb traditional floor lamp with 60W incandescents pulls 180 watts.

Desk lamp: Most modern desk lamps are integrated LED at 5 to 12 watts. Older gooseneck or banker-style lamps with halogen pulls 20 to 50 watts.

Nightlight: 0.3 to 4 watts depending on type. A 0.5W LED nightlight left on 24/7 costs $0.79 a year. A 4W incandescent nightlight costs $6.32 a year.

Smart bulb (color-changing): 8 to 12 watts on full white, 3 to 6 watts on warm dim. Standby (Wi-Fi listening) draws 0.3 to 0.5 watts. A smart bulb left off but plugged in costs about $0.50 a year per bulb in standby.

The two questions homeowners actually ask: does it matter if I left a lamp on overnight, and does it matter if I left one on for a whole weekend trip?

Lamp on overnight (10 hours). A 9W LED costs $0.016. A 60W incandescent costs $0.108. Nobody is losing sleep over either number, but the incandescent is 6.7 times more wasteful than it had to be.

Lamp on for a 3-day weekend (72 hours). A 9W LED costs $0.12. A 60W incandescent costs $0.78. Across an annual habit of leaving a single lamp on for weekends away (say 20 weekends a year), the incandescent is $15.60 of waste. The LED is $2.40.

Lamp on 24/7 for a year. A 9W LED costs $14.22 a year at national average. A 60W incandescent costs $94.80. A 100W incandescent (still common in high-ceiling fixtures) costs $158. This is the scenario where the difference becomes a meaningful chunk of an electric bill.

The pattern is consistent. With LED bulbs, leaving lights on is a non-event in dollar terms. With incandescent bulbs, it adds up to real money over years. With halogens, it lands in between. The behavioral fix (turn off the lights) matters far less than the hardware fix (replace the bulb).

The numbers above use the U.S. national average. Your actual cost depends on your state rate, which varies more than most homeowners realize. The April 2026 EIA Electric Power Monthly puts Louisiana at 12.44¢/kWh and Hawaii at 39.79¢/kWh. Same appliance, same hours, three times the cost.

A 60W incandescent left on 24/7 for a year:

Louisiana (12.44¢/kWh): $65 a year per bulb. National average (18.05¢/kWh): $94.80 a year per bulb. California (~31¢/kWh): $163 a year per bulb. Hawaii (39.79¢/kWh): $209 a year per bulb.

A 9W LED left on 24/7 for a year:

Louisiana: $9.80 a year. National average: $14.22 a year. California: $24.45 a year. Hawaii: $31.36 a year.

The high-rate states are where bulb choice goes from "saves a few bucks" to structurally important. A homeowner in Hawaii running ten 60W incandescents 5 hours a day spends about $436 a year on lighting. The same fixtures with 9W LEDs cost about $65. That is a $370 annual delta on a single category. The electricity rates by state guide has the current 2026 number for every state.

A 60W incandescent bulb produces about 800 lumens of light. A 9W LED produces the same 800 lumens. The incandescent uses 6.7 times the wattage to do the same job. The extra energy is not lost in the wire or the socket. It comes out of the bulb as heat.

The DOE Energy Saver puts incandescent efficiency around 10%. The other 90% is heat radiating from the filament. That heat is why old incandescent bulbs got hot enough to burn skin, why they were a fire risk in fabric shades, and why summer-cooling costs in incandescent- lit rooms were measurably higher than in LED-lit ones. An LED bulb runs cool because it converts a much larger share of input watts into actual visible light.

The ENERGY STAR LED lighting reference program certifies LED replacements at specific lumen-per-watt thresholds, which is how you get apples-to-apples comparisons across brands. A 9W LED is the ENERGY STAR equivalent for a 60W incandescent. A 13W LED replaces a 75W. An 18W LED replaces a 100W.

Lighting accounts for roughly 15% of an average home's electricity per the DOE. That share has dropped sharply over the past decade as LEDs replaced incandescents, which is why the most expensive appliances list is now dominated by HVAC, water heating, and refrigeration rather than lighting. The LED vs. incandescent yearly cost breakdown runs the multi-bulb whole-home math.

Three observations from running these numbers across hundreds of household configurations:

1. The bulb is the lever, not the switch. Reminding the family to turn off lights saves a couple of dollars a year if the bulbs are LEDs. Replacing incandescents with LEDs saves $40 to $200 a year on the same fixtures. Time spent on the second question dwarfs time spent on the first.

2. The wattage label on the bulb tells you the cost. A 9W LED is 9 watts. A 60W incandescent is 60 watts. There is no surprise math. The RunWatts calculator handles the bulb, hours, and your state rate automatically, but you can do this one on the back of an envelope.

3. Smart bulbs are not a meaningful cost. Standby draw of 0.3 to 0.5 watts per bulb costs about $0.50 a year. A 12-bulb smart-home system in standby is $6 a year. Whether to buy them is a feature question, not an electricity-cost question.

For the underlying wattages of every common household appliance, including the lamp, floor lamp, and bulb categories, the appliance wattage chart has the full reference. For the calculator side of this, every bulb and lamp in the 141-appliance database is duty-cycle adjusted (lamps run at full wattage when on, so there is no adjustment needed for them) and uses your state rate.

Leaving a lamp on costs about $0.39 a month for 8 hours a day with a 9W LED at the national average rate. The same lamp with a 60W incandescent costs $2.60 a month, and $7.80 a month if you leave it on around the clock. The difference is the bulb. Replace it once and the question stops mattering.

The table lamp calculator runs the math at your state's actual rate, with bulb-type presets for LED, incandescent, halogen, and CFL. The 9W LED bulb calculator covers the per-bulb annual cost across multi-bulb configurations.