Good Lumens, Bad Lux

In my current occupation, we develop handheld and hands-free portable lighting solutions.

That’s a technical way of saying we make flashlights and headlamps.

And we talk about lumens all the time. All…The…Time.

Just like octane at the gas pump, lumens of a flashlight are the number 1, 2, and 3 factors that consumers care about.

Let’s say we build an amazing flashlight. We sit down with an end user and show them the superior ergonomic grip, the long-lasting, rechargeable high capacity battery, and the rubber, grippy switch that seamless moves you from brighter to dimmer, and back to brighter light. When the presentation is over they’ll ask….”What’s the lumens?”….and not even fake-it that they didn’t hear anything else.

Lumens drives decision making. The higher the lumens, the higher the price (or greater the value). More isn’t always better - which I’ll write about in a later post.

So what are “Lumens”?

Lumens are a measure of the total amount of visible light emitted by a source. It represents the brightness of a light source. Hence, a measure of the amount of light generated from the flashlight (or headlamp, lantern, etc..). Since we produce the “light source”, that is a measurement we care about.

A different mesurement of light, which you may have heard, is the term “Lux”. Lux is a measure of illuminance. Think about the amount of light hitting a surface. It represents the intensity of light in a specific area

Recall the last time you went to a live theater performance. You could have seen a play, a comic, or a rock band. Typically, the performer is under intense light - the limelight. The measurement of light on that performer, is called Lux. The light emitting from the lit lime - ok, I know they don’t burn lime anymore - well this light is measured by lumens.

Lumens are lumens, but lux aren’t lux. Lumens produce a light, and that’s the lumens. Lux is dependent on where it’s being measured. An easy example is:

• Lumens: A 1000 lumen bulb emits the same total light output whether it's used in a small room or a large hall.

• Lux: The same 1000 lumen bulb will produce higher lux (more concentrated light) in a small, confined space compared to a large, open area.

Lumens are an important consideration in the design of the light emitting product. On the other hand, Lux is an important consideration in the design of a space receiving light.