Lux vs. Lumens – The Great Debate!

The Truth About Lux Vs Lumens – Auxiliary Vehicle LED Lighting

LED Driving Lights and Light Bars vs. LUX – An accurate measurement, but more has to be considered.

The short answer:

Remember these 3 things when choosing any lighting to suit long-distance driving or even crawling through tight tracks at night:

1. Look at LUX figures, not Lumens.
2. Look at the beam pattern, ensure it will suit what you need to do.
3. If it sounds too good to be true, it is!


The technical response:

LUX is defined as being the measurement of light intensity, as perceived by the human eye. It is the measure of light at a given distance on a surface, usually defined to 1LUX. LED lighting manufacturers have pushed aside Lumens in favour of LUX (Lx) and has become the latest buzzword in the LED lighting scene. LUX distance data is an important metric but is misleading if considered out of context.

When driving light manufacturers perform photometric testing to obtain ISOlux data, the testing equipment used only measures the peak luminous intensity at the centre point of the beam, what about the rest of the beam? If 3 different driving lights project 1000m at 1LUX, which one do you invest in? To obtain great ISOlux figures, it’s simply a matter of focusing down the beam. However, a focused beam can be at the cost of a useable beam pattern. The very best driving lights are the ones which project the most useable balance between brightness (Lm) and light projection (Lx).

The best driving light isn’t necessarily the one that achieves the longest light projection. The best driving light is designed to project light where is needed most, therefore one must consider their driving style and what is required from their lighting setup. If you are one that never really ventures from winding mountainous roads, you may consider a more euro or elliptical beam pattern, rather than pencil or spot.


I have more Watts; therefore, my lights are brighter…

We have all seen the ridiculous ads on eBay, 102,400w 40-inch LED light bar. Not to mention, this bar also has 210,000 lumens! We’re going put this absolute nonsense to rest.

3 Facts:

  • Watts & Lumens have no relationship. 
  • Watts & Lux have no relationship.
  • LED’s in this context use printed circuit boards, comprising of multiple components. The catalyst is actually how hard the diodes are driven at, controlled by the integrated circuit driver. In most basic forms, LED would be considered ‘smart’ against an incandescent filament type bulb.

In brief terms, Watts is a measurement of the amount of energy consumed by any given luminaries. We are used to looking at Watts to determine light output, due to the past 100 years of incandescent.  With this older style technology, it is correct to assume that 100 Watt light bulb is likely to be brighter when compared to an 80 Watt bulb.  When it comes to LED, it’s correct that Watts is the measurement of input power, but the same thinking has no connection to the output.


LED Driving Lights and Light Bars vs. Lumens – Only a small consideration in the performance metric.

Lumens (lm) is the measurement of light emitted from the source.

The American National Standard Institute international standard for measuring lumens is in an integrated sphere, in other words, the lumen output is measured at a close proximity to the source of the light. The lumen rating is only a consideration in determining the brightness of the led lamp, and shouldn’t be the only deciding factor when choosing which LED Light Bar.

We must consider the usability of any LED lighting that we are looking to invest in. Either Lumens, LUX or Watts cannot be solely considered. Considering the usability of your LED light bar or driving lights is much more important. Projecting light 100-400m down the road is much more important than ratings and arbitrary figures that some of these sellers seem to pull from thin air.

You will find a quality light manufacturer will base their specifications and accreditations from practical tests. Accredited LUX data and effective lumens is data we should be seeking. Testing two driving lights side by side with equal lumen data, but different lens or reflector configurations can greatly alter the intensity of light (LUX) at 250m.

In short, the delivered light (lux) is the more accurate measurement for usability.