We quote lifetime in hours of use. 1,000 hours is reckoned to be equivalent to 1 year's use and is the normal lifetime for traditional incandescent bulbs. LED bulbs are rated at 20,000 - 50,000 hours and our compact fluorescent bulbs at 8,000 hours. However, these figures are only indicative and are not a guarantee. The standard measure of bulb life is the time taken for 50% of a statistically significant sample to fail. For example, a rated life of 8,000 hours indicates that 50% of bulbs should be expected to last 8,000 hours or longer.

Compact fluorescent bulbs work best if they are left on for at least 15 minutes as they take a few minutes to warm up and reach maximum efficiency although this is often not apparent to the user. More frequent switching on and off will shorten the product's life.

LED lifespan is more complex. LEDs slowly lose their brightness over time. In general the higher quality (and more expensive) the LED the slower loss of brightness occurs. So for example CREE state that their better quality LEDs might lose about 30% of their brightness in 50,000 hours. These figures are necessarily estimated based upon extended running tests of a few thousand hours. There are 8,760 hours in a non-leap year so testing LEDs to destruction is simply not possible without waiting years for the results. Low cost LEDs will tend to lose their brighness faster and we usually try to reflect this in the rated hours. Our budget 48 LEDs, which are similarly priced to low energy compact fluorescent lamps are designed to operate at a high brightness for a while, however this design feature means that they will also lose their brightness much faster than had we started with a lower brightness. The various SMD LED bulbs offer a good compromise between the extended life of the high quality, high power LEDs (ours are usually CREE) and the faster burn of the budget low power LED lamps.