A Free Calculator · Your Bulbs, Your Rate · Updated 2026
How much do LED bulbs really save you?
Swapping incandescent or CFL bulbs for LEDs cuts the power each fixture draws — and
that adds up fast on bulbs you run for hours. Enter how many bulbs you're replacing,
the old and new wattages, your daily usage, and your electricity rate, and the
calculator returns your savings per year, over ten years, the energy you'll save, and
the CO2 you'll avoid. Every formula is shown, nothing is hidden.
Savings per year & over 10 years·Energy saved & CO2 avoided·Your own electricity rate
Read this first
The energy savings here are exact for the inputs you enter. But LEDs also last
far longer — roughly 25,000 hours versus about 1,000 hours for an incandescent — so you
buy and replace far fewer bulbs over the years. This tool counts only the
electricity savings; the bulb-replacement savings are extra on top (see the FAQ).
The CO2 figure uses a U.S. average grid factor (about 0.82 lb per kWh) and is approximate —
your region's grid may be cleaner or dirtier, so treat that number as a typical estimate,
not a measurement.
Tell the calculator how many bulbs you're swapping, the wattage of the old bulb versus the new LED, how many hours a day they run, and your electricity rate. The results update as you type.
Your bulbs & usage
bulbs
How many identical bulbs you're replacing with LEDs.
hrs/day
Average daily run time for these bulbs. Most-used fixtures save the most.
Pick a common bulb to fill the wattage below; you can still edit it.
W
The bulb you're replacing — a standard old bulb is ~60 W.
W
A 60 W-equivalent LED is about 8–10 W. Check the box for the actual figure.
Nothing here is a black box. These are the exact calculations the tool runs — the same
arithmetic you could do on paper. The only judgment calls are the inputs you supply and
the grid CO2 factor, which is a labeled U.S. average.
How each number is derived
Named constants
WATTS_PER_KILOWATT = 1000
DAYS_PER_YEAR = 365
PROJECTION_YEARS = 10
CO2_LB_PER_KWH = 0.82 // U.S. average grid CO2 per kWh (EPA eGRID national avg, approximate; varies by region)
A quick reference for the usual replacements. The "Saved/yr per bulb" column assumes a
single bulb running 3 hours a day at $0.17/kWh — change any of those in the calculator
above and your numbers will differ. LED wattages are typical figures for a bulb
that matches the old one's brightness; check the package for your bulb's actual draw.
Old bulb
LED equivalent
Watts saved
Saved/yr per bulb (3 hrs/day, $0.17)
40 W
~5 W
35 W
$6.52
60 W
~9 W
51 W
$9.49
75 W
~12 W
63 W
$11.73
100 W
~15 W
85 W
$15.82
LED equivalent wattages are typical and vary by brand and lumen output — buy by lumens,
not watts (see the implications below). Per-bulb savings use the formulas above:
(old − new) ÷ 1000 × 3 hours × 365 days × $0.17. Multiply by the number of identical
bulbs you have, or just use the calculator.
Why the savings add up
LEDs win in three ways at once. The calculator above measures only the first — electricity —
but the other two are real money and worth knowing before you buy.
The savings scale with hours — target your most-used fixtures first
A bulb's savings are directly proportional to how long it runs. A porch light, kitchen fixture, or living-room lamp that's on many hours a day saves far more than a closet or attic bulb you flip on for seconds. If you're switching bulbs gradually, do the high-use fixtures first: a single porch light left on overnight can save more than a dozen rarely-touched bulbs combined. Plug your real daily hours into the calculator to see which fixtures justify a swap soonest.
LEDs cut replacement cost too
This tool counts electricity only, but LEDs last roughly 25,000 hours against about 1,000 hours for an incandescent — about 25 times longer. Over the life of one LED you'd burn through a stack of incandescents, so you save on bulb purchases and on the chore of changing them, which matters most for hard-to-reach or high-ceiling fixtures. Those replacement savings vary by bulb price, so we treat them as a bonus on top of the energy figure rather than folding a guess into the math.
Brightness is lumens, not watts
Watts measure the power a bulb draws; lumens measure the light it produces. The whole point of LEDs is producing the same lumens for a fraction of the watts. When you shop, ignore the "60W equivalent" headline and check the lumen number: about 800 lumens replaces a 60-watt incandescent, 1,100 replaces a 75-watt, and 1,600 replaces a 100-watt. Matching lumens — not watts — is how you get the same brightness while drawing far less power.
How to make the switch
A short, practical order of operations — from counting bulbs to disposing of the old ones
properly.
Count the bulbs you're replacing
Walk the house and tally how many bulbs of each type you have — grouping by old wattage and by how many hours they run. The calculator handles one group of identical bulbs at a time, so a quick inventory tells you where to start.
Note the wattage you're replacing
Read the old bulb's printed wattage (40, 60, 75, or 100 W is typical for incandescents; 14–23 W for CFLs). That number, minus the new LED's wattage, is your per-bulb savings driver. The preset dropdown above fills in common values for you.
Pick the LED by lumens, not watts
Match the lumens of your old bulb — about 800 for a 60-watt incandescent — and choose a color temperature (warm ~2,700K for living spaces, cooler 4,000K+ for work areas). The LED's own wattage will be far lower; enter it in the calculator to confirm the savings.
Prioritize high-use rooms
Replace the bulbs that run the most hours first — kitchen, living room, porch, hallway. Those deliver the biggest savings per dollar spent on bulbs, so even a gradual switch pays back quickly when you start there.
Recycle or dispose of old CFLs properly
Incandescents can go in the household trash. CFLs contain a small amount of mercury and should be recycled, not tossed — many hardware stores and municipal programs accept them. If a CFL breaks, ventilate the room and follow safe cleanup guidance rather than vacuuming it up.
Where to buy
Got your numbers? Here's where to pick up what you need:
The units and terms that show up on a bulb package, a spec sheet, or an electric bill —
in plain English.
Watt (W)
A unit of power — the rate at which a bulb draws electricity. A 60 W incandescent and a 9 W LED can produce the same light, but the LED draws far fewer watts. Watts are what you multiply by hours of use to get energy in kilowatt-hours, which is what you pay for.
Lumen (lm)
A unit of light output — how bright a bulb actually appears, regardless of how much power it uses. Roughly 800 lumens replaces a 60 W incandescent, 1,100 a 75 W, and 1,600 a 100 W. Shop for LEDs by lumens, not watts.
Kilowatt-hour (kWh)
A unit of energy — one kilowatt (1,000 watts) drawn for one hour. It's the unit your utility bills you in, at a price per kWh. A 60 W bulb running 1 hour uses 0.06 kWh; the savings in this calculator are measured in kWh per year.
LED
Light-emitting diode — the bulb technology that produces light electronically with very little waste heat. LEDs use about 75–85% less energy than incandescents for the same brightness and last roughly 25 times longer, which is why they dominate the lighting aisle today.
CFL
Compact fluorescent lamp — the curly bulbs that preceded LEDs as the efficient option. CFLs use less energy than incandescents but more than LEDs, take a moment to warm up, and contain a small amount of mercury, so they should be recycled rather than thrown in the trash.
Incandescent
The traditional bulb that makes light by heating a filament until it glows. It wastes about 90% of its energy as heat, lasts only around 1,000 hours, and is the most expensive bulb to run — which is what makes switching to an LED worthwhile.
Color temperature (Kelvin)
A measure, in kelvin (K), of how warm or cool a bulb's light looks — not how hot it gets. About 2,700K is a warm, yellowish glow like an old incandescent; 3,500–4,000K is a neutral white; 5,000K+ is a cool daylight white. It doesn't affect energy use or the savings here.
Wattage equivalence
The "60W replacement" label on an LED package — a shorthand telling you which old incandescent it's meant to match in brightness. It's a marketing convenience; the trustworthy numbers are the LED's actual wattage (what it draws) and its lumens (how bright it is).
Frequently asked
It depends on how many bulbs you swap, the wattage gap, how long they run, and your electricity rate. A single 60-watt incandescent replaced by a 9-watt LED saves 51 watts. Run 3 hours a day at $0.17/kWh, that one bulb saves about $9.49 a year. Swap ten such bulbs and you save roughly $95 a year — about $949 over ten years — while cutting around 558 kWh and avoiding roughly 458 pounds of CO2 each year. The savings scale directly with your inputs, so the calculator above uses your own numbers rather than an average. The biggest lever is hours of use: a porch light or kitchen fixture that runs many hours a day saves far more than a closet bulb.
For high-use fixtures, usually yes. An incandescent bulb wastes about 90% of its energy as heat, so a working incandescent is quietly costing you money every hour it's on. If a bulb runs several hours a day, the electricity savings from an LED often pay back the bulb's purchase price within months. For a bulb you rarely use — a closet or attic light — the payback is much slower, and replacing it on failure is reasonable. Prioritize your most-used fixtures first; that's where switching working bulbs actually pays. Use the calculator above to see the yearly savings for your specific situation before deciding.
Buy by lumens, not watts. Watts measure power drawn; lumens measure light output. A traditional 60-watt incandescent produces about 800 lumens, a 75-watt about 1,100 lumens, and a 100-watt about 1,600 lumens. Packaging usually lists a watt equivalence (e.g. "60W replacement") and the actual lumen output. Match the lumens of your old bulb and you'll get the same brightness while drawing far fewer watts — typically 8 to 10 watts for a 60-watt-equivalent LED. If a room feels dim after switching, you bought too few lumens, not the wrong technology.
Yes. This calculator counts only the electricity savings, but LEDs also last far longer — commonly rated around 25,000 hours versus roughly 1,000 hours for an incandescent, about 25 times longer. That means you buy and replace far fewer bulbs over the years, saving on bulb purchases and on the hassle of changing them, which matters for hard-to-reach fixtures. The replacement savings are real but vary by bulb price and brand, so they're treated as a bonus on top of the energy figure here rather than folded into it. LEDs also produce much less waste heat, which can slightly reduce summer cooling load.
Color temperature, measured in kelvin (K), describes how warm or cool a bulb's light looks — it has nothing to do with how hot the bulb gets. Lower numbers (around 2,700K) give a warm, yellowish glow similar to an old incandescent, which most people prefer for living rooms and bedrooms. Middle values (around 3,500K to 4,000K) are a neutral white good for kitchens and bathrooms. Higher numbers (5,000K and up) are a cool, bluish daylight white suited to garages, workshops, and task lighting. LEDs come in all of these, so check the kelvin rating on the package to match the mood you want; it does not affect energy use or the savings in this calculator.
Yes — dimming an LED reduces the power it draws, so a dimmed LED costs less to run than one at full brightness, and the savings versus an incandescent only grow. But two cautions apply. First, only LEDs labeled dimmable should go on a dimmer; non-dimmable LEDs may flicker, buzz, or fail early. Second, older dimmers were designed for incandescent loads and may not dim LEDs smoothly across their full range — an LED-compatible dimmer fixes most flicker and buzzing. The calculator above assumes a fixed wattage; if you dim regularly, your real savings will be a bit higher than it shows.
Common mistakes with this calculator
LED savings estimates are easy to inflate or misdirect — here's where the math typically goes wrong.
Matching watts instead of lumens — and ending up with a dim room
The whole point of LED is that you get the same light output (lumens) from far fewer watts. If you simply replace a 60 W incandescent with a 60 W equivalent LED, you've done it right. But if you replace a 60 W bulb with a 10 W LED that produces only 650 lumens when the room needed the original 800, you've "saved" electricity but dimmed your space. Match the lumen output, not just the wattage label. Source: ENERGY STAR minimum lumen requirements for replacement bulbs.
Calculating savings on low-use bulbs while ignoring high-use fixtures
Replacing 10 closet bulbs used 15 minutes a day yields almost nothing. Replacing the 4 recessed fixtures in the kitchen or the porch fixture left on all evening is where real money is. Sort your bulbs by hours per day first and prioritize the top of that list — the calculator will show the savings difference clearly.
Treating a 10-year projection as inflation-adjusted
The savings shown are calculated at today's electricity rate, held flat for the full projection period. Electricity prices have risen on average roughly 2–3% per year historically, so actual 10-year savings will likely be higher than shown — but the calculator does not model that. Don't interpret the flat-rate projection as a conservative floor; it's simply a single-rate estimate.
Assuming the CO₂ figure applies to your local grid
The carbon savings calculation uses a U.S. average grid emissions factor (about 0.82 lb, or 0.37 kg, CO₂ per kWh — an EPA eGRID national-average figure). Your actual grid may be significantly cleaner (hydro-heavy Pacific Northwest, high-renewables states) or dirtier (coal-heavy grids). The kWh and dollar savings are accurate regardless; only the CO₂ figure varies by region. Source: EPA eGRID.