Yes, turning off lights saves money every single time you do it. The savings per bulb are small, but they add up across every room in your home and every hour of the day. How much you save depends almost entirely on what type of bulb you’re switching off and how long it stays off.
How Much One Bulb Costs to Run
The average U.S. residential electricity rate is about 13.6 cents per kilowatt-hour in 2025, according to the Energy Information Administration. To figure out what a single light costs you, multiply the bulb’s wattage by the hours it’s on, then divide by 1,000 to get kilowatt-hours. Multiply that by your electricity rate and you have your cost.
Here’s where bulb type matters enormously. To produce the same 800 lumens of light (the brightness of a classic 60-watt bulb), different technologies pull very different amounts of power:
- Incandescent: 60 watts
- CFL: 13 to 15 watts
- LED: 8 to 10 watts
An incandescent bulb left on for 8 hours costs roughly 6.5 cents. An LED producing the same light costs about 1 cent over those same 8 hours. That gap is the reason your bulb type determines whether turning off lights saves you dollars or just pennies over a year.
Real Savings Across a Household
Let’s say you have 20 light fixtures in your home and you get into the habit of turning off lights in empty rooms, saving an average of 4 hours of unnecessary use per fixture each day. With LEDs at 10 watts each, that habit saves you about 0.8 kilowatt-hours per day, or roughly 292 kilowatt-hours per year. At 13.6 cents per kWh, that works out to about $40 annually.
If those same 20 fixtures still had 60-watt incandescent bulbs, the identical habit would save around 1,752 kilowatt-hours per year, worth roughly $238. That’s a meaningful chunk of an electricity bill. Even if you’ve already switched to LEDs, $40 is $40 you’re not getting back by leaving lights on for no reason. And in states like Connecticut or California where residential rates run well above 20 cents per kWh, these numbers climb proportionally.
The “Startup Surge” Myth
You may have heard that flipping a light on uses a burst of energy that cancels out the savings of turning it off. This is one of those ideas that has a tiny kernel of truth but wildly overstates the effect. The inrush current when a bulb powers on lasts about a tenth of a second and uses roughly as much energy as five seconds of normal operation. So if you turn off a light for more than a few seconds, you’re already coming out ahead on energy.
The real concern with frequent switching isn’t energy use. It’s bulb lifespan. Incandescent bulbs and CFLs wear out faster when they’re switched on and off frequently, because the filament or electrode degrades with each power cycle. The Department of Energy notes that for CFLs, you should weigh the cost of a shorter bulb life against the savings from turning it off. A common guideline is to leave CFLs on if you’ll be back within 15 minutes.
LEDs, however, don’t have this problem at all. Their operating life is unaffected by switching cycles. You can turn an LED on and off as often as you like with zero impact on how long it lasts. This makes LEDs ideal for rooms you pop in and out of, and it’s why they pair well with motion-sensor switches.
The Hidden Cost: Heat From Your Bulbs
There’s a second way leaving lights on costs you money that most people overlook. Incandescent bulbs convert most of their energy into heat rather than light. A single 60-watt incandescent produces about 85 BTUs of heat per hour, compared to just 3 BTUs per hour from an equivalent LED. That heat warms your room, which means your air conditioner has to work harder to remove it during summer months.
One estimate puts the additional cooling cost of a single 60-watt incandescent at nearly $14 per year compared to its LED equivalent. Multiply that across a house full of old bulbs and the AC penalty alone can rival the direct lighting cost. During winter, you might think that heat is a bonus, but incandescent bulbs are an extremely inefficient heat source, costing roughly five times more than a typical gas furnace to generate the same warmth. Turning off unnecessary lights reduces both the direct electricity draw and the secondary cooling load.
Incandescent Bulbs Are Going Away
If you’re still running incandescent bulbs, this context matters: Congress passed the Energy Independence and Security Act in 2007, directing a phaseout of inefficient incandescent bulbs. The Department of Energy has issued updated standards that will require compliance by 2028, effectively completing the transition away from standard incandescents. Specialty bulbs like oven lights and bug lights are exempt, but the classic household incandescent is on its way out. Switching to LEDs now captures the biggest possible savings, because you’re eliminating both the high wattage and the heat load in one move.
Where Turning Off Lights Matters Most
Not every light switch flip saves equal amounts. Focus your attention where it counts. High-wattage fixtures like bathroom vanities with multiple bulbs, kitchen ceiling lights, and garage or basement lights that tend to get left on for hours are your biggest opportunities. A six-bulb vanity using 10-watt LEDs draws 60 watts total. Left on for an extra 5 hours a day, that single fixture wastes about $15 a year. If those were still incandescent bulbs at 60 watts each, that same vanity would waste over $90 annually.
Outdoor lights are another frequent offender. A porch light left on from dusk to dawn for 10 hours uses more energy than most people assume when multiplied across an entire year. Putting exterior lights on a timer or motion sensor eliminates the waste without requiring you to remember the switch.
Smart plugs and occupancy sensors are worth considering for rooms where lights routinely get forgotten. Since LEDs handle frequent switching without any lifespan penalty, automation is a perfect fit. The sensors themselves cost a few dollars each and pay for themselves within months in most households.