What does Lux mean?

If you’re asking “What does lux mean?”, read on for the answer…

If you are considering LED lighting, it’s vital to achieve adequate lux levels.

But was does lux mean?

Lux is basically a measure of how well a given location is illuminated.

Our short guide explains lux, illuminance, lighting design, and more.

What does Lux mean?

by David Lewis, Chief Strategy Officer | first published 7 February 2019 | revised 29 February 2024

What does Lux mean? An Example

How lux affects lighting

I am currently sitting at a desk and there are 450 lux on the desk surface (measured by a light or lux meter).

I have two lights shining on the desk and if I turn one of them off, the lux level goes down to 290 lux. In effect, my desk surface gets darker and I can’t see as well.

So lux levels are all about how much light I feel around me. If it’s dark, lux levels are low. If it’s bright, lux levels are high.

This is a good day-to-day definition of lux.

Lux Lighting Levels

Measuring lux

How do you measure lux? LED lighting surveyors will use light meters to measure lux. They will take lux readings from various points in a room, to gauge how lux levels vary across the space. Using DIALux software, you can then present a ‘before and after’: showing the customer the lux levels with current lighting and then what they would be with LED lighting.

Definition of Lux – The Science



If you ask a scientist “What does lux mean?”, you’ll get a more complicated answer.

Lux is an SI unit – like metres, kilograms, etc. – that measures ‘luminous flux’ per unit area. You will find more information about luminous flux on our guide explaining lumens. 1 lux = 1 lumen per square meter. This definition of lux is already getting confusing…

Lux, in essence, is about ‘illuminance’ – how intensely a given surface is illuminated. If there are more lumens in a square metre of my table (i.e. it’s brighter), then lux levels are higher.

Cut to the chase

Summary: forget the science bit. What does lux mean to you? More lux = brighter. Less lux = darker.

Over time, lux levels will get lower with any type of lighting, although LED lighting is very resilient.

LED Lighting Design

Software ensures accuracy

When designing LED lighting for a customer, you need to consider first what lux levels would be appropriate in each location, and then how to achieve those lux levels.

The Chartered Institution of Building Services Engineers (CIBSE) provides guidelines for suitable lux levels for a variety of applications: office work, engineering, warehousing, etc.

If CIBSE recommends 150 lux in a loading bay, for example, you then need to use software, such as DIALux, to work out how to achieve 150 lux at the height staff will be working at.


Better working environment

What, therefore, does lux mean to a member of staff working in that loading bay? It means a properly lit, safe working environment. That’s perhaps the best definition of lux.

If you are considering an upgrade to LED lighting, make sure the companies you are talking to have discussed lux levels with you and provided DIALux reports guaranteeing those lux levels will be achieved. You also need to consider which colour temperature would be appropriate for different settings.


Understanding lux is basically about considering how well any given area is illuminated.

Getting lux levels right in the workplace is a vital part of safe, healthy, productive working. Too little light can lead to headaches, squinting, or – in the worst cases – accidents.

Having your building properly audited by a trained professional, using a light meter, followed up by a detailed design using the right lighting software is the best approach to ensuring the correct lux levels.

Safe lighting in the workplace