While it can vary slightly depending on the bulb, on average LED light bulbs last over 50,000 hours. That would be almost six years if left on twenty-four hours, seven days a week. In terms of usage, if you leave your light on all day (16 hours), an LED replacement bulb would last 3,125 days or approximately 8.5 years. If you leave it on only during the evening (4 hours), an LED replacement bulb would last 35 years. Comparatively speaking, both incandescent and compact fluorescent light bulbs last a mere fraction of that. LEDs last 50 times longer than a traditional incandescent bulb and 10 times longer than a compact fluorescent.