Lumens vs. Lux – Know The Actual Difference Between Them?

If you’ve ever heard of the terms lumen and lux, you probably had some doubts about what they meant. And you wouldn’t be the only one asking such questions. That happens to practically anyone who’s not familiar with light engineering.

But don’t worry. Not knowing what these light terms mean is actually good. It means there’s a lot of space for learning, and that’s precisely what you will do with this article.

Here, we’ll explain lumens vs lux, what each term means and how you can separate them accordingly. If you are eager to learn more about this and get your head around these two confusing concepts, then read on and find out!

lux vs lumens


This term refers to illuminance. It is often used as an (lx) or lux. And it measures the light that reflects in a specific area. In fact, lux is one lumen per square meter. We’ll go over lumens later. But keeping that in mind will give you a better idea of what lux means.

Depending on the number of lumens a lamp can create, you can calculate how much lux it will provide in a specific area. If a lamp is over a desk, for example, and it produces 100 lumens, then you could say that it will create 100 lux per square meter on the desk.

But if the lamp is hanging on the ceiling and illuminates a 4-square-meter desk, then it won’t produce 100 lux, but only 25 lux in that specific area.

You could say that lux is the amount of visible light on any surface. It measures the power of light devices and systems. And it tells you how well something can light up depending on how far it is located from the area to measure.

To get a better idea, let’s measure the lux you get from the moon. Usually, a full moon on a clear night sky can produce about one to two lux of visibility on the surface. But in full daylight with a clear sky, sunlight can provide up to 100,000 lux on the earth’s surface.

lux vs lumens

Have a better idea now? Well, we hope so. Now, let’s get into lumens so you can have an even better understanding of what we’re talking about.


When it comes to measuring light brightness, there’s no other unit to think about than lumens or (lm). This will tell you how bright a light can be. The brighter the light, the more lumens it has.

To put it simply, a lumen is the amount of light any light source can produce. And it doesn’t care about the area or the direction; it just gives the total amount of light coming out of the source directly.

Let’s give an example. When trying to tell how much lumens a headlight produces, you won’t care about where the light illuminates or how much area it covers. Instead, you will have to focus on the light source and how much brightness it creates.

Of course, the more brightness (or more lumens) any light source has the more area and the more illuminance it will create. But there are hundreds of factors to consider here, so lumen refers only to the source and how much light it can produce.

It is sort of difficult to understand, but nothing impossible. If you have a better idea now, then let’s head up and learn how lumens and lux work together and how they differ.

lux vs lumens

Lux vs Lumens: Differences & Similarities

So, now that you are more familiar with what lux and lumen mean, it is time to make a much better example of how they differ.

Let’s say you have a 1,000-lumen lamp in your office. If you place the lamp in front of a single square meter, then this lamp will grab the 1,000 lumens to produce exactly 1,000 lux in the single square meter.

That means that the lamp produces 1,000 lumens that cover one square meter with 1,000 lux.

But once you separate the lamp from the surface and make it light up from farther away, then the 1,000 lux per square meter start becoming 500 lux for two meters, then 250 lux for four meters, and so on.

Now that you have a 1,000-lumen lamp illuminating 5 square meters, you won’t get 1,000 lux per meter, but only 200 lux.

Lumen is how much light something produces. Lux is how bright the surface will be according to the amount of light that the light-source creates.

lux vs lumens

When to Use

By now, you should be an expert in light engineering with our previous explanations. But don’t worry if you aren’t. We’re going to make it even easier to know which one is which by teaching you how you can use each one accordingly.

As said before, lumens are the amount of light or brightness that comes out from a source. You will only use it to tell how much power a bulb, lamp, lantern, or any type of light produces.

Whenever you want to know how much brightness a light source produces, then you’ll use lumens. Of course, lumens are necessary to understand whether a bulb or lamp will be enough or not for a place. But lumens don’t work alone – you will need lux in that case.

Now, for calculating the amount of light that a place will need to illuminate completely, you will have to consider the size, length, and distance of the light source. Then, you’ll finally have a specific amount of lux by subtracting these factors from the number of lumens.

Let’s say you have a massive 100-square-meter office. You want to illuminate it completely so that it looks bright enough for any kind of activity – in this case, office work.

lux vs lumens

If there are 100 square meters and you want everything to be as bright as possible, you’ll want at least 100 lumens per square meter. That would be 100 lux in the 100-square-meter area. To produce that amount, you will need at least 10 bulbs of 1,000 lumens. That would be enough to produce 10,000 lumens in total. And here’s a good post If you’re interested in knowing how many lumens a projector needs.

So, to produce 100 lux per 100-square-meters, you will need at least 10,000 lumens. Of course, many other factors enter into play. But that would be a standard calculation.

Lux then refers to the amount of light that falls into the surface of the office (100 lux), coming out directly from the ten 1,000 lumens bulbs.

That’s how you need to use lumens vs lux if it ever becomes necessary. Lumens for the amount of light something emits, and lux for how much surface that light can cover.


This can be somewhat difficult, or maybe not. But still, it is necessary to understand if you’re ever considering building up a projector at home, engineering the light for an entire work area, or just trying to figure out how much light you will need in a specific room.

As long as you know that a lumen is the light brightness level and a lux is the covered surface of that brightness, then you’ll be safe doing these calculations.

Up Next: How to get sound from the projector to the speakers?

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