(pronounced LU-men)

It’s easy to remember that this word relates to lighting and the emitting of light – just think of words you probably already know such as luminaire, luminaria and luminary. What’s not as easy is grasping exactly what a lumen is. In the most basic sense, a lumen (abbreviated “lm”) is a measurable unit of light just like a centimeter is a measurable unit of distance or a BTU is a measurable unit of energy. In a more technical sense, a lumen is the amount of light (a.k.a. luminous flux) that is spread over a square foot of surface by one candle when all parts of the surface are exactly one foot from the light source. More lumens = more light. Just to give you an idea, a dinner candle imparts about 12 lumens, a 60-watt soft white incandescent lamp imparts about 840 lumens, and a 100-watt incandescent lamp imparts about 1700.