Understanding Lumen, Lux, and Candela

You just got a new car and are eager to throw in some new LED headlights.  You find a source and see ‘4000 lumens per bulb’ and are probably scratching your head wondering, “What are lumens?”

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This is a question we see often and it’s definitely something to be looking at when planning on upgrading any lamps to an aftermarket LED bulb.

First, you must understand that there is more than 1 method to measure light and certain methods call for a specific scenario in order to understand how to measure the light to give you an idea of what type of lighting results you will see.

The most common methods at measuring light are Lumens, Lux and Candela.

What are Lumens?

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Lumens is total amount of light emitted by the light source.

Lumens is the preferred method to measure light for most manufacturers that produce aftermarket LED products as this is the simplest to calculate for most and easiest to understand for any professional mechanic or auto enthusiast that is new to the industry.

Lumens is the unit of measure of light which provides a total rating for light that is visible to the human eye or the total amount of light emitted by the source for short.  A flash light can produce an average of 1000-1500 lumens which gives you an idea of how much it will throw.  Most of our LED headlights produce an average of 4,000 lumens and go as low as 2,000 lumens or as high as 6,000 lumens depending on the design and what you need for your vehicle.  Smaller LEDs for interior produce an average of 50-220 lumens.  For aftermarket LEDs, lumens is the total amount of light being emitted by the diodes.

What is Lux?

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Photo credit by Instagram User @decams_grands_wj

Lux is short for luminous flux.  Lux is the total amount of light that hits a surface.  Let’s take your vehicles backup lights as an example.  You just installed an LED bulb that shines about 500lm per bulb.  If you take a flat piece of card board that is roughly 1 square meter then your readings will measure to 500 lux per bulb for light hitting the card board.  If you step back a few feet to where the light then hits 4 square meters or 4 pieces of card board then it will divide total lumen or 500 lux by 4 and give you a lux reading of 125 lux per bulb.  This essentially reduces light concentration among each square meter but covers a larger surface area.

As mentioned earlier, there are several factors that come into play when measuring lux and some cars are not fully stock especially those who love to mod there vehicles.  Sometimes you have 4in lift kits that changes height, or an aftermarket housing that focus the light differently to increase lux.  Other examples would be distance or angle of the light emitted.

lux and lumens

Lux is the total amount of light that hits a surface.

For this reason, most automotive lighting manufacturers prefer to provide a lumen rating but if you go to a local hardware store and want to pick up a flash light or a bulb for your living room, the lux ratings are usually displayed since the scenarios are very common for those type of applications regardless of how they are used.  For automotive, it’s a different game due to the factors that come into play such as the housing, bulb design, and/or light source.

Lux is good to understand so you will know how far out your backup lights shine or even your LED light bars but remember the distance from the surface and angle of the beam are the most common factors that will determine actual lux readings.

What is Candela?

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Candela is a professional term for candle power.  Candela is another unit of measure for light and not something automotive manufacturers prefer to use but definitely good to understand for anything related to lighting such as aftermarket automotive LEDs.  Candela is an obsolete unit of measure of light due to lumen ratings, however, for applications like law enforcement vehicles and/or aviation vessels are categories where this is used.  This would benefit other applications that need light noticeability or to be seen at a distance.

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High candela ratings are essential for lamps found in planes, helicopters, and emergency type vehicles.

Candela is the measurement to describe how bright the light source is.  You are probably thinking, “Is this not the same as lumens?”  There is definitely a difference between both. Lumens is total light emitted.  Candela is total light emitted that is visible at a distance to understand how bright the light source is capable of.   You can say candela is a way to describe brightness rather than how much light is emitted.  1 Candela is equivalent to light emitted by 1 candle.

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1 Candela is equivalent to light emitted by 1 candle.

A better way to understand candela is to take a laser pointer as an example.  The light from a laser will not be bright at all.  If you back up a 100 feet or so, you will still be able to see the light from the laser at a distance since all light emitted is concentrated to a single and small area.  Even at a distance, the concentration of light is still focused to a small area allowing you to see the laser.  The candle power, or candela will be very high, however, lumen and lux ratings will be low.

Next time you are in the market to upgrade your lamps to LED, don’t just scratch your head and research to figure this out.  Let us do the work for you!  We can guide you and help you find the best LED light source for your car to help improve drive safety, visibility, and brilliance.

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Photo credit by Instagram Sponsor @uptomyassinbrass.

And remember….

‘LED JDM ASTAR light your way on the road!”



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