Prior to LED technology, incandescent or halogen bulbs would "burn out" when they reached the end of their life. LED bulbs do not generally burn out. Instead, the intensity of their light output begins to fade over time.
What is Lumen Maintenance?
Lumen Maintenance is a measurement used to evaluate the decrease in light output of a bulb that occurs over time. LED light bulb life is defined as when the light bulb produces 70% of the initial lumens (L70). This measurement lets you know how long you can depend on an LED to provide an acceptable level of intensity as the day you installed it.
What is an L70 Rating?
LED must maintain 70% of their initial lumens during their rated life. For example, an LED with a life of 25,000 hours means that at 25,000 hours of use, the LED bulb will be producing 70% of the light output that it was producing when it was brand new.