Lux vs. Lumens in a Projector

Beth Huston Profile image

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Updated December 8, 2022

Comparing lux vs lumens in a projector requires understanding these two similar but fundamentally different technical terms. While both are photometric measurement units, there are some significant differences. This article will serve as a quick guide to get you ready to purchase a new projector. Why is this important? Well, there are several projector models on the market, and you’ll need this information to decide accurately on the best projector for you. Digital projectors, theatre projectors, and all other types rely on lumens and lux to perform.


  • Lumens essentially refer to luminous flux, which is defined as the light levels produced by your projector over a unit of time.
  • Lux is similar to lumens rating but refers to brightness in terms of how bright a projected image appears when spread out over the surface area of your screen.
  • Both lux and lumens are considered SI-based units used to measure brightness levels and are often used in conjunction with one another.

Comparing Lux and Lumens

Lux and lumens are closely related, but while they are both relevant to projectors, each one measures light slightly differently. Using both helps determine if your projector of choice has the luminous intensity to overcome existing ambient light. For example, knowing how many lumens are in an outdoor projector allows you to see if it would be a good model to use outside. 

However, also knowing which projector connections, such as VGA vs HDMI, work best in an outdoor setting is also useful. 

Insider Tip

Business projectors are a fantastic addition to any office that will drive engagement for your teams. But before you buy, you can compare some high-end brand projectors, like the BenQ HT5550 vs Epson 5050UB, to find the right one for you. 

Why These Units of Measurement are Important

Neither unit is notably better than the other as a measurement. Instead, they work together to determine whether a light source is genuinely bright enough to overcome ambient lighting. They measure the same light source but provide two different aspects of it. Of course, luminosity isn’t the only thing you need to get excellent image quality from your projector. Knowing how to improve color accuracy with a projector will help immensely.

Defining Lux and Lumens

Luminous flux is the amount of light emitted per second in all directions by a light source. Luminous flux is measured in lumens, so the lumens rating of a projector describes how bright a light it can produce. In other words, it describes how strong the projector’s beam of light is.

However, you don’t use a projector without a screen; this is where lux comes in. Lux describes the brightness of that same light beam once it’s spread across the screen. If you want more details on lux, check out our guide on how many lux is good for a projector.

Which Is More Accurate for Light Projection?

While measuring the brightness of your projector’s light source is great, it doesn’t give you the complete picture. Light loses brightness as it travels through the air. This is why the lux rating is a far better indicator of your projector’s image quality.


What level of brightness should portable projectors have?

When it comes to portable projectors, you want a relatively high light output. You’ll never be able to compare with models like theatre projectors, but they should at least be reasonably high. We recommend at least 500 lumens for fairly dark locations, but more is always better. For locations with some unavoidable ambient light, 2,000 lumens or higher is recommended.

How can I tone down ambient light around projector screens?

Ambient light can spell disaster for excellent viewing conditions. Locate all light sources in the room, such as light bulbs, and either remove, turn off, or significantly dim them. Covering all windows as best you can and limiting reflective surfaces will help, as well.

Do I need a high-lumen projector for my lifestyle?

It really depends on the location in which you plan on using your projector. If it’s a fairly dark, small space, a lower-lumen rating of 500 lumens will be fine. For large spaces or areas that will have some ambient light, a projector with 2,000 lumens or more is best. Higher lumens translate to brighter on-screen images.

Does screen size matter when it comes to image quality?

A large screen might increase visibility simply through size. However, the intensity of light emitted from your projector matters far more. Device resolution is the real determining factor.

STAT: Lumens are related to lux in that one lux is one lumen per square meter. (source)


While visible light is ordinarily harmless, high-intensity light output can be damaging to your eyes.

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