LED FAQs (Part 2): LED Lifetime

et cetera...: You can’t measure an LED lifetime in the same way as an incandescent light bulb. Instead of burning out, a properly cooled and powered LED will fade very slowly over time, lasting tens of thousands of hours.

So rather than measuring an LED’s life by when the emitter completely burns out, LED users have decided that once an LED device drops below some threshold – usually (but not always) 70% brightness – the LED can be considered a “burn-out.” This brightness threshold is generally expressed as ‘L70’ in specifications.