Raw Lumens and Effective Lumens on a Work Lamp Spec Sheet

What the Two Figures Mean

Raw lumens is the output of the bare LED chips at the drive current and junction temperature used in the test. Effective lumens is what leaves the finished lamp after the lens, the reflector and the thermal conditions inside the housing have taken their share. Every Dantech spec sheet that carries both numbers lists them separately for that reason.

Why the Gap Exists

Light is lost at three points. The polycarbonate lens absorbs and reflects a share of what hits it. The reflector or optic redirects light, and redirection is never free. And the LED itself produces less light hot than cold, so a lamp measured after it reaches steady temperature reads lower than one measured at switch-on. A gap of roughly twenty per cent between raw and effective figures is normal for a sealed die-cast work lamp.

How to Compare Two Lamps Honestly

Compare effective lumens against effective lumens, or raw against raw. Comparing one supplier's raw figure with another supplier's effective figure makes a lamp look forty per cent better than it is. If a datasheet gives only one number and does not say which it is, treat it as a raw figure until the supplier confirms otherwise.

Lumens Are Not the Whole Answer

A spot lamp and a flood lamp with identical lumen figures light completely different areas. On a machine, what matters is whether the beam covers the working envelope of the attachment at the distance you actually work at. Read the beam pattern line on the spec sheet alongside the lumen figure, never on its own.