The Real Cost of Leaving Lights On All Day (2024 Numbers)

TL;DR: A single incandescent bulb left on around the clock costs roughly $63 a year at the national average rate of 16.5 cents per kWh; an LED doing the same job costs about $9. Most of the "just leave it on" advice from decades past doesn't hold up anymore, and the real waste in most homes is a mix of forgotten porch lights, closet fixtures, and old bulbs that were never swapped for LEDs.

_Last reviewed: July 2026 · 6 min read_

You flip a switch out of habit, not need, and it adds up faster than it looks on paper. Landlords with vacant units and homeowners with grown kids who leave every room lit both ask the same question: is it actually costing me money, or is this just an old wives' tale? The math says yes, it costs money, and the amount depends on the bulb, the rate, and how many fixtures are involved.

Okoniq Property Hub logs your utility costs by unit and by month, so you can spot a spike before it turns into a pattern across a whole rental portfolio.

How much does leaving a light on all day actually cost?

A standard 60-watt incandescent bulb run 24 hours a day uses about 1.44 kWh daily, or roughly 526 kWh a year. At the U.S. average residential rate of 16.5 cents per kWh (EIA, early 2024 data), that's about $63 annually for one bulb. Run five bulbs that way across a house and you're looking at over $300 a year, which is real money for something nobody's actually using.

The number changes fast with the bulb type. A 9-watt LED that puts out the same brightness as that 60-watt incandescent costs closer to $13 a year run continuously, and most LEDs rated for equivalent output actually draw closer to 8-10 watts. Halogens sit in between, usually 40-43 watts for the same lumens, landing around $45-$50 a year. The bulb matters more than the habit.

Is it cheaper to leave lights on than turn them off and on?

No, this is a myth left over from an era of different bulb technology. The idea that switching a light on repeatedly "uses more energy" or "shortens bulb life" more than leaving it running was true, to a small degree, for old fluorescent tubes with magnetic ballasts, which did take a small surge to start and suffered from frequent cycling. It was never true for incandescent bulbs, and it's not true for LEDs either.

LEDs have no meaningful startup surge and no filament to degrade from switching. Turning a light off for even a few minutes saves more energy than any theoretical cost of the "restart." If you're still running old fluorescents in a garage or basement, that's a separate maintenance question worth pairing with 5 appliances quietly running up your electric bill, since those spaces often hide more than one energy drain at once.

Does leaving lights on all day cause other problems besides the bill?

Yes, heat and fixture wear are the two overlooked costs. Incandescent and halogen bulbs convert most of their energy into heat, not light, which means a room with several bulbs running constantly can add measurable warmth in summer, working against your air conditioning. LEDs run much cooler, but even they generate some heat at the driver, and running any fixture 24/7 shortens its practical lifespan compared to normal on/off use.

There's also a fire-risk angle that matters more for older homes. A bulb rated for 60 watts screwed into a fixture only rated for 40, left running nonstop in an enclosed fixture, builds heat over months in a way that occasional use never would. If your home still has older wiring behind those fixtures, it's worth checking 5 signs you still have knob-and-tube wiring in your home, since heat buildup interacts differently with older circuits than modern ones.

| | Incandescent (60W) | LED (9W equivalent) | |---|---|---| | Annual cost, run 24/7 | ~$63 | ~$13 | | Typical lifespan | 1,000 hours | 15,000-25,000 hours | | Heat output | High | Low | | Cost to replace | $1-$2 | $3-$6 |

What's the smartest way to cut this cost without changing habits?

The fastest fix is swapping bulbs before trying to change behavior, since behavior change rarely sticks but a $4 LED swap does. Start with any fixture that's already known to stay on for hours, porch lights, hallway fixtures, closets people forget, and garage lighting. A house that swaps 10 commonly-used incandescent bulbs for LEDs can save $400-$500 a year at current rates, which is a bigger return than most home maintenance projects for the same upfront cost.

For landlords, this is a per-unit calculation worth tracking separately, especially in units where the landlord pays utilities directly or where common-area lighting (stairwells, laundry rooms, parking lot lights) runs continuously by design. A motion sensor or timer on common-area fixtures often pays for itself within the first year, and it's a smaller, faster project than most electrical upgrades, unlike something on the scale of 100 vs 200 amp service: do you have enough power?, which is worth planning for separately if you're already rewiring.

FAQ

Is it bad to leave a light on all night?

Not dangerous by itself if the bulb and fixture are properly rated, but it does cost money continuously. A single LED left on overnight for 8 hours costs a fraction of a cent, while an incandescent bulb doing the same costs closer to 2-3 cents per night, which adds up to real dollars over a year.

How much does a porch light cost to run all year?

A 60-watt incandescent porch light run 12 hours a night costs roughly $31 a year at the national average rate. Switching to an LED equivalent drops that to around $5-$7 a year, and pairing it with a dusk-to-dawn sensor removes the guesswork entirely.

Do LED bulbs really last longer than the packaging claims?

Most quality LEDs rated for 15,000-25,000 hours do reach close to that lifespan under normal household use, though heat and poor ventilation in enclosed fixtures can shorten it. That's still 15-25 times longer than a typical incandescent bulb rated for 1,000 hours.

Should landlords cover the cost of tenant-left lights?

That depends on the lease terms and who pays the utility bill, but landlords who pay utilities directly benefit most from swapping to LEDs proactively rather than relying on tenants to change habits. It's a low-cost, one-time fix compared to ongoing monitoring.

What's the single fastest way to lower a high electric bill tied to lighting?

Replace the bulbs in your most-used fixtures first, since a handful of high-use LEDs will cut more cost than swapping every rarely-used bulb in the house. Combine that with timers on porch and garage lights for the biggest first-year savings.

This is educational information, not financial advice. Talk to your utility provider or a licensed electrician if you have questions about your specific rate plan or wiring.