Flashlight FAQ: What Is Lux in a Flashlight?

What is Lux in a flashlight?  When buying a new flashlight, packaging terms such as lumens, lux and candela are common.  One of them, lux, is oftentimes, used in determining how bright the product could be. Actually, lux is something more than that. Keep reading.

What is lux in a flashlight?

It indicates the how intense light is distributed and is measured at the beam’s center.  Additionally, lux indicates how far the throw of the light will be.

When comparing flashlights with the same lumen ratings, you can also check on “lux” for more help in determining spot illumination differences. The higher the lux the better will be its spot illumination/flood illumination.

However, consumers find it confusing to compare torches using lux alone. For help, read the following section to spot the differences in the different lighting terms you’d find in the packaging.

Flashlight Terms: It’s More Than the Lux Value to Know

Lumen (LM)

This standardized measurement indicates how much light can be produced by the light source, let’s say, a LED light.  In a more technical term, it is the “luminous flux” measurement of the flashlight. Represented in an equation,

1 candela * 1 Steradian = 1 lumen

• Steradian, 1/12.566^th of one sphere; it is the unit of measure, which equals a solid angle subtended at a sphere’s center by a surface area of the sphere, which is equal to the radius squared.
• Candela, measure of light intensity

Some makers indicate lumens as OTF, out the front, meaning it used the output out the lighting product’s front.  It is contrary to lighting intensity   measured through bulb ratings or emitters.

Lux (LX)

This indicated the luminous flux of the lighting source over an area’s unit.    It tells us about high the intensity of the light is distributed. The measurement of the lux is often done at the beam’s center.

In an equation, 1 lx = 1 lm/sq m

Foot Candles (FC)

Some models use FC instead of LX. It is the measure of lumens/one sq ft.

In an equation, 1 fc = 1 lm/sq ft, where an fc is equal to 10.764 lux

Candela (CD)

It is the luminous intensity of the lighting source. In the past, a candela was the intensity of light from a traditional candle, and so the term candela.

The term has been standardized. Now, it means luminous intensity of the source emitting “540 x 10^12 hertz frequency of monochromatic radiation.” Luminous intensity has a radiant intensity in that direction “1/683 watt per steradian,” according to the NIST.

Some lighting products, flashlights included, will have this measurement for the flashlight beam’s center.  So aside from determining lumens, knowing candela will also help you determine the throw of that product.

In short, candela rating can also guide you when comparing the floodlight and spotlight properties of flashlights with the same lumen ratings.

For a strongly focused lighting source, you may want to find a candela over lumen ratio of more than 100.

Tactical flashlights, on the other hand, are offered with a ratio 20-100, while one with less than 10 can be on work lights for close-up lighting.

What to Remember

• Many flashlight brands and models use lumens to specify brightness, while others use Lx. In many cases, both are used. Either way, you know by now the differences between these lighting terms and what they tell you about the light produced by the product.
• Check for lumens, not the wattage of the flashlight. Wattage does not have anything to do with the amount of light it can produce.
• Oftentimes, torches also have one or more light sources, as well as lenses and reflectors. In that case, the beams they produce aren’t the same across products even with equal lumen ratings.
• There are makers that claim higher lumen amount than what is actually being given by the flashlight. [Lumens can measure the total light output, while lux can tell you of its intensity. Knowing about lumens rating alone won’t be the sole factor for light quality the source can emit.]

Final Thoughts

When buying a torch, look into lux, not only lumens.  Hope this guide on “what is Lux in a flashlight” helps you make a sound decision and buy based on knowledge in comparing even tactical flashlights that have the same lumens but different lux value. Always remember, lux measures the light output amount in a given unit of area (wherein one lx = one lm/sq ft).

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