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LED lifespan has been a hotly debated subject since coming into mainstream use. The question shouldn’t be why LEDs last so long. We should be asking why all the other bulbs burn out so quickly. When Thomas Edison unveiled his bulb for the world to see, its lifespan was somewhere around 1200 hours. In the 130 years since then incandescent lifespan hasn’t improved much. What makes LED technology so superior to those already in use? We first need to take a closer look at what we have been using.

    Incandescent Bulbs

 Metals expand when heated and contract when cooled; they have what is called a coefficient of thermal expansion. When an incandescent light bulb (ILB) is turned on, the thin tungsten filament coiled up inside rapidly heats up and glows white hot filling a room with light. Each time the light is turned on or off the expansion and contraction causes metal fatigue until the filament breaks. When that happens we say the bulb ‘burned out’.

 Think about it, don't ILBs always seem to burn out precisely when they are turned on? You may see a blue flash or hear an audible clink when it goes. That is metal fatigue in action.

 Higher quality ILBs are either evacuated or filled with a relatively inert gas like nitrogen. The filament then does not come in contact with oxygen. Hot metal oxidizes in the presence of oxygen gas, and oxidation in ILBs produces tungsten oxide which vastly shortens the life of the filament.

  Some older ILBs look dark inside. That dark material on the inside surface of the glass is material from the metal filament itself. Tungsten atoms constantly evaporate from the filament, when on, and are deposited on the inside of the glass envelope. The already thin filament continues to become thinner and thinner until at some point it is too thin and breaks the conductor, ruining the ILB.

Cheaper ILBs last 750 to 1,000 hours or less than a year of normal usage. Long life span ILBs can be up to 1,500 to 2,000 hours, but they cost a lot more. Still, they last only about 2 years with normal use.

 Fluorescent & CFL Lamps

Fluorescent lights and compact fluorescent lights (CFLs) have a similar burn out scenario as ILBs already discussed.

          If you have ever replaced old burned out 4 foot or other length glass fluorescent tubes (T5s, T8s or T12s) you would have noticed a blackening at either or both ends of the old tube. The blackening is from evaporation of the shielded metal filaments at either end of the tube.

          CFLs have no filaments but have electrodes instead that emit electrons into the gas inside the glass. The electrodes are also subject to evaporation as time goes on. In some cases either the starter (if it has one) or the ballast has gone bad. However the fluorescent tube or CFL itself will eventually burn out.

          Manufacturers have been steadily improving the life spans of fluorescent and CFL lighting. The average rated life span of a CFL is between 6 and 15 times typical ILBs. CFLs nominally have a rated life expectancy of 6,000 to 15,000 hours (q.v. Wikipedia 'Compact fluorescent lamp').

LED Lights

LEDs (Light Emitting Diodes) are altogether a horse of a different color, they NEVER burn out! LEDs have no filaments, no metal fatigue, no oxidation and no evaporation of electrical components. Both ILBs and CFLs are fragile and have to be handled like eggs. On the other hand LEDs are robust, very rugged, solid state devices with no glass to break. However, LEDs will stop working if placed next to an atomic explosion.

  LEDs are made on substrate semiconductor materials such as GaAs (Gallium-Arsenide). There are two doped regions, P – positive and N – negative. When current passes through the PN junction it causes electrons to jump to higher atomic energy states. When the electrons return to the ground state, light in the form of photons is emitted. This phenomenon is called electroluminescence and it consumes very little energy since very little heat is generated. LEDs have no problematic filaments, no wear or tear, nothing is changed or altered hence they keep on working for extraordinary long lengths of time.

          If LEDs never burn out, why do they even have a stated life expectancy rating at all, even if very high like 30,000 or 50,000 or even 100,000 hours?

          Generally, the life expectancy rating of all light bulbs is based on a year of 1,100 hours usage because 365 days per year times an average of 3 hours a day usage comes out to exactly 1,095 hours.

Lamp Type:

Hours of Life Expectancy:

Years of Life Expectancy:

End of Life span Result:




70% of original brightness




70% of original brightness




70% of original brightness








Burn out




Burn out








Burn out




Burn out


Though LEDs don't burn out, their brightness slowly decreases over their long life spans. LEDs might last for a thousand years but they will be operating at 70% brightness when they have reached the full term of their expected life.

So the question isn't "Why Do LED Lights Last So Long?", rather the question should be "Why do ILBs and CFLs burn out so soon?”.


Coefficient of thermal expansion – a number assigned to the amount of thermal expansion, the degree of expansion (See thermal expansion).

Electroluminescence – is an optical / electrical phenomenon in which a material emits light in response to the passage of an electric current or an electric field.

Fluorescence – is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. In most cases, the emitted light has a longer wavelength, and therefore lower energy.

Incandescence – is the emission of light from a hot body due to its temperature.

Metal fatigue – is the tendency of a metal, to crack under stress, bending or vibration.

Photon – a particle or ray of light or electromagnetic radiation.

Thermal expansion – is the tendency of matter to change in volume in response to a change in temperature. All materials have this tendency.

Tungsten – a metallic element, atomic symbol W.