Theoretical Lumens Output is the calculated sum of the LEDs’ nominal luminous flux before losses in the driver, optics, lens, and thermal operating conditions are taken into account. It is an upper-reference value and should not be treated as the complete lamp’s delivered output. See Operational Lumens Output. The value may be obtained by multiplying the nominal output of one LED by the number of LEDs, often using laboratory conditions specified by the LED manufacturer. It is useful during design but can overstate delivered performance. Comparisons between finished work lights should therefore prioritize operational lumens measured for the complete lamp under stated conditions.