LED vs Fluorescent vs Halogen: Efficacy, Life, and Light Quality
LED, fluorescent, and halogen lighting compared — lumens per watt, rated life, CRI, dimming, heat, and disposal, with per-fixture cost drivers.
Updated August 20, 2026
Three generations of lighting technology are still sold side by side, and the physics gap between them is enormous: a halogen lamp is a heater that happens to glow, converting most of its wattage to heat and only 15–25 lumens from each watt; a fluorescent tube excites phosphors with a mercury-vapor discharge and roughly triples that; an LED emits light directly from a semiconductor junction and, in current retail lamps, delivers on the order of 80–150 lumens per watt.
Efficacy is only half the ledger — the other half is how long each source lasts and what the light looks like. Halogen dies youngest (a few thousand hours) but renders color perfectly, because it is a true blackbody radiator with CRI 100. Fluorescent lives ten times longer but carries mercury, hums through a ballast, and hesitates to full brightness. LED outlives both by rating, dims deeper than fluorescent ever could, and has quietly matched the color quality that once justified halogen accent lighting.
The purchase price ranking runs exactly opposite to the operating cost ranking, which is why the comparison below itemizes cost drivers instead of declaring a single winner per row: a lamp that burns four times the watts for a tenth of the life can still make sense in a fixture that runs an hour a year — and almost nowhere else.
Side by Side
| Spec | LED | Fluorescent (CFL/linear) | Halogen |
|---|---|---|---|
| Luminous efficacy (lm/W, typical published range) | ≈80–150 for retail lamps; DOE SSL program products exceed this | ≈55–70 (CFL); ≈80–100 (linear T8/T5 with electronic ballast) | ≈15–25 — a modest gain over plain incandescent |
| Rated life (hours, published range)LED "life" is rated to 70% lumen output (L70), not burnout — a different failure definition than filament or discharge lamps. | 15,000–50,000 (L70 lumen-maintenance basis) | 8,000–15,000 (CFL); 20,000–36,000 (linear tubes) | 2,000–4,000 |
| Color rendering (CRI, typical) | 80–90 standard; 90+ widely available | 80s for tri-phosphor products; older halophosphate tubes far lower | 100 — a continuous blackbody spectrum by nature |
| Warm-up & dimming behavior | Instant on; dims smoothly to low levels with a compatible dimmer/driver pairing | Noticeable run-up to full brightness (worst for CFL in cold); dimming needs special ballasts and stays limited | Instant on; dims perfectly on any incandescent dimmer, warming in tone as it dims |
| Heat output share | Lowest — waste heat is conducted to the heatsink, not radiated into the room or beam | Moderate — ballast and tube losses | Highest by far — the overwhelming share of input watts leaves as heat, with a quartz capsule running hot enough to be a burn and fire consideration |
| Mercury content & disposal | None — ordinary e-waste handling | Contains mercury — take-back or hazardous-waste recycling, and broken-lamp cleanup guidance applies | None — ordinary trash where local rules allow |
| Cost drivers (purchase vs operating) | Highest sticker per lamp, lowest lifetime cost: watts and relamping labor both collapse | Cheap lamps, but ballasts age and fail separately and disposal has a real cost | Cheapest to buy, costliest to run: maximum watts per lumen plus the most frequent replacement of the three |
Which One for the Job
Whole-home bulb swap-out
LED
Across dozens of sockets running hours a day, the efficacy gap compounds into the largest lighting saving available in a house, and the 15,000-hour-plus ratings mean ladders come out once a decade instead of every season. Screw-base LED now covers every common shape, beam, and dimmer scenario the other two served.
Shop or garage high-bay task lighting
LED
This was linear fluorescent’s stronghold, but cold-start behavior decides it: tubes sulk at winter garage temperatures while LED reaches full output instantly at any temperature that concerns a human. High-bay LED fixtures also drop ballast maintenance entirely — the component that actually fails first in aging fluorescent shops.
Accent lighting where beam quality dominates
LED (halogen only for niche fidelity)
Halogen earned this niche with CRI 100, crisp point-source beams, and dim-to-warm behavior. Modern 90+ CRI LED MR16 and PAR lamps replicate all three closely enough for nearly all display work at a quarter of the watts and heat on the artwork; halogen remains defensible only where an exact blackbody spectrum is itself the requirement.
Existing fluorescent troffer ceiling that still works
Either
A functioning T8 system with fresh tubes is not an emergency — tri-phosphor tubes on electronic ballasts are respectably efficient, and the marginal saving may not repay ripping out serviceable fixtures immediately. The decision point is the next ballast failure: at that moment, retrofitting to LED beats buying another ballast on almost every input.
Frequently Asked Questions
What does an LED lamp’s rated life actually promise?
Not the hour it goes dark. LED lifetimes are quoted to L70 — the projected point where light output has faded to 70% of initial — because LEDs dim gradually rather than burning out. A 25,000-hour rating therefore means "still delivering at least 70% of its lumens at 25,000 hours," and premature outright failures are almost always the driver electronics, not the diodes.
Do fluorescent tubes really need special disposal?
Yes — every fluorescent lamp, CFL or linear, contains a small amount of mercury sealed in the tube, so most jurisdictions require recycling through retail take-back or household-hazardous-waste programs rather than the trash. A broken lamp calls for airing the room and careful pickup per EPA cleanup guidance. LED and halogen contain no mercury.
Why does my dimmer buzz or flicker with new LED bulbs?
Old incandescent dimmers chop the AC waveform in a way filament lamps smooth out and some LED drivers cannot. The fix is pairing: use LED lamps marked dimmable and a dimmer listed for LED loads (or from the lamp maker’s compatibility list), and respect the dimmer’s minimum load. Mismatched pairs produce the flicker, buzz, and narrow dimming range the technology gets wrongly blamed for.
Is halogen ever still worth buying?
Rarely, and the window is closing — several markets have phased halogen out of general sale. Its surviving arguments are a perfect CRI-100 spectrum, dirt-cheap purchase price for rarely-used fixtures, and drop-in behavior in ovens and appliances where electronics cannot survive the heat. For any socket that runs regularly, its wattage and short life make it the most expensive light per lumen-hour of the three.
Try the Calculators
Sources
- DOE Energy Saver — lighting choices and LED lighting pages: efficacy and lifetime comparisons for LED, CFL, and halogen incandescent
- DOE Solid-State Lighting program publications — LED efficacy trajectories and L70 lumen-maintenance life definition
- ENERGY STAR lamp specification (certified bulb criteria) — minimum efficacy, life, and dimming/CRI requirements for qualified CFL and LED lamps
- EPA guidance on mercury-containing fluorescent lamp recycling and broken-lamp cleanup