What Are Lumens & Why Do They Matter?

Sep 5, 2018

Category: Tech

When it comes to everyday carry gear, there are a few things we believe every person should carry. Typically, that includes some kind of wallet, a cutting tool or multi-tool, a pen or other writing utensil, and a flashlight. The latter, however, is often overlooked and (most definitely) the most underrated of the bunch. Considering that most humans spend about half of their lives in the dark — granted much of that time is spent asleep — we think it’s a tremendous shame.

For those in the know, a flashlight is immensely useful when it comes to illuminating dark paths, finding dropped items under dark desks, and even as a means of self-defense. But even amongst the EDC community, there is much about these portable torches still to learn. Perhaps the largest and most important is the concept of lumens. Sure, we all know that lumens are related to a flashlight’s light output — but that’s usually about as far as the knowledge goes. As we believe that understanding the concept of lumens is of the utmost importance both for choosing the right flashlight for ourselves, as well as educating others as to their importance — we’ve decided to illuminate the subject in the following guide. This is everything you need to know about lumens.

Measuring Light

A Simple Explanation

If you’ve found yourself asking what, exactly, lumens are and you went to the trouble of looking it up, there’s a pretty good chance things were not cleared up much, if at all. If you haven’t, allow us to educate. The Merriam-Webster Dictionary defines lumens as, “a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of one candle intensity.” What you should glean from the dictionary definition is this: lumens are a measure of light brightness.While you might be able to scratch your head and extract a few tidbits of new information out of that definition, we non-scientists find it a lot easier to understand the concept in laymen’s terms.

What you should glean from the dictionary definition is this: lumens are a measure of light brightness. Granted, there’s more to it than that — for instance, a measurement of one lumen is equivalent to the light emitted by a single stationary candle uninterrupted by obstruction and measured in total, regardless of the direction in which the light is traveling. For our purposes, however, the nuances of the definition are not important. All you need to know is that more lumens means greater brightness. One lumen is half as bright as two lumens, two is half as bright as four, four is half as bright as eight, etc. In that way, it’s similar to horsepower measurements in relation to car engine performance — and that’s a pretty easy association to help you understand how they function.

It’s also important to note that a single lumen is a fixed unit. That is to say, while a flame might fluctuate its brightness as it burns, a single lumen does not fluctuate in its measured value. That also means lumens can be measured in fractions —  a single lumen is not the smallest possible value of light brightness (you’ll often see flashlights that emit as little as 0.5 lumens). When it comes to directional light, like flashlights, the value of lumens is calculated from the total light output — measured across the entire beam, whether that light is considered useful or not (as with the furthest edges of the beam).The higher the number of lumens, the greater the brightness. Similarly, unidirectional bulb lumen output is measured in total — not just from a single point.

As previously mentioned, the larger takeaway from all this is that lumens are a measure of overall brightness output by a given source — be that a flashlight, bulb, or even a television. The higher the number of lumens, the greater the brightness. For reference, direct sunlight is equivalent to about 10,000 lumens. However, when it comes to flashlights, somewhere around the 60 lumens mark is enough light for most people to complete basic tasks in the dark. According to most flashlight brands, 80 lumens is the beginning threshold for temporarily blinding a person (which varies from situation to situation depending on environmental factors), though — when it comes to self-defense applications — some companies will suggest as high as 500 lumens to temporarily disorient an assailant.

What Happened To Watts?

Change Is Good

If you are of an older generation or your understanding of lighting is the result of learning from your parents or grandparents, you might be confused as to when and how lumens replaced watts as a measurement of lightbulb output. In truth, lumens represent a relatively new system of measurement, at least in regards to consumer products. Years and years ago, incandescent bulbs were not measured by the output of the light itself, but rather in the amount of electrical energy needed to power them —Incandescent bulbs were not measured by the output of the light itself, but rather in the amount of electrical energy needed to power them. hence measuring lightbulbs in regards to watts. When LED lights started replacing traditional incandescent ones, watts were still the measurement of choice and remained that was until quite recently.

Unfortunately, as evidenced by the invention of LED lights, watts is not an accurate representation of light output. Often, low-wattage LED lights will actually be brighter than their higher wattage incandescent counterparts. It is likely this development that led companies to start measuring light output separately from power usage. Now, there is still a correlation between the two (at least to a degree). Typically, higher wattage bulbs will put out greater amounts of light — so long as the bulbs being compared utilize the same light-emitting technology (e.g. a 20-watt LED is dimmer than a 60-watt LED). But, at the end of the day, lumens is the more correct lighting metric, as it is intrinsic to the emitted light itself, whereas watts are only somewhat related to the overall output.

Lumens vs. Candelas

What's The Difference?

Here’s where things get a little tricky. If you’ve been ingrained in the world of everyday carry or have worked in the illumination industry, you’ve probably heard of the term “candela.” While the two terms (lumen and candela) are significantly more intertwined than lumens and watts, there are still some distinct differences from one another. Namely, the difference can be found in both where and how the two are measured.

The definition of candela (again, from the Merriam-Webster Dictionary) is, “the base unit of luminous intensity in the International System of Units that is equal to the luminous intensity in a given direction of a source which emits monochromatic radiation of frequency 540 × 1012 hertz and has a radiant intensity in that direction of ¹/₆₈₃ watt per unit solid angle — abbreviation cd — called also candle.” Once again, this is a confusing definition, but we can clear it up a bit.Lumens are the numerical measurement of total light output. A candela is the measure of light intensity in relation to the distance at which you can view it. Lumens, as you might remember, are the numerical measurement of total light output. A candela, by contrast, is the measure of light intensity in relation to the distance at which you can view it.

Since lumens are a total measure of output, they don’t depend on the distance at which you view that light. A 1,000-lumen flashlight puts out 1,000 lumens whether you’re looking at it from point blank or a mile away. Candelas, however, are entirely dependent upon distance viewed from a single angle. To express this, we suggest comparing the light of a lit candle with a laser pointer. When viewed from a great distance, the light from a candle might be difficult to see. However, a laser pointer that outputs the same total lumens may still be visible at a greater distance because all of that light is concentrated in a single focused beam.

Well-Rounded Measurements

Why Lumens Are Important

Since there are so many ways to apply quantifiable value to a light-emitting device, why is it that we use lumens as the most important measurable metric? Simplicity and functionality. The distance at which light is thrown from a light-emitting device is certainly important (and is most often represented by a ‘beam distance’ metric), but it’s not nearly as useful as the total output measurement,The measurement of lumens gives a well-rounded impression of the total value of a light-creating device in figures that are both comprehensible and relatable. as most users find themselves needing only to illuminate a few feet in any given direction. Similarly, power usage is an outdated metric that doesn’t necessarily apply to the light created by your device of choice.

By contrast, the measurement of lumens gives a well-rounded impression of the total value of a light-creating device in figures that are both comprehensible and relatable. While there are definitely nuanced technical differences between the two, it’s a small leap to create a relatively accurate mental correlation between the lumen output number and the overall brightness of a bulb, flashlight, etc. As such, lumens sit at a distinct intersection between technical accuracy and ease of understanding.

15 Best Rechargeable EDC Flashlights

A flashlight is an everyday carry necessity, but they can be made all the more enticing if you don’t have to constantly change the batteries. And that’s why we encourage everyone to take a gander at our list of the best rechargeable EDC flashlights — that way you’ll never have to be in the dark.

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