Lumen vs Lux – Difference and Lighting Guide

Lumen and Lux: Understanding the Difference for Perfect Lighting

Light, a Matter of Measurement

When choosing a lamp or bulb, you’ll often come across the terms lumen and lux. These two technical notions can be confusing, but they are complementary. Understanding the difference helps you pick the right lighting for each room, depending on the ambiance and usage.

What is a lumen (lm)?

The lumen is the unit that measures the total luminous flux emitted by a light source. In simple terms, it’s the total amount of light produced. A lamp rated at 800 lumens emits twice as much light as a lamp rated at 400 lumens, regardless of how that light is distributed.

Lumens indicate the perceived brightness of a fixture: the higher the number, the brighter the light.

What is a lux (lx)?

The lux measures the illuminance on a surface. In other words, it expresses how much light (lumens) falls on one square meter.

Simple example:

A 1000-lumen lamp lighting a table of 1 m² = 1000 lux.
The same lamp spread over 10 m² = 100 lux.

Lux takes into account not only the amount of light but also how it is spread across a given space.

The difference between lumen and lux

The distinction is simple:

Lumen = how much light a lamp produces.
Lux = how much light reaches a surface.

So, a strong lamp can feel weak in a large room if the light is spread too thinly, while a smaller lamp can be very effective in a compact space.

Lumens, watts, and LED bulbs

In the past, watts were used as a reference to estimate brightness, especially with incandescent bulbs. For example, a 60W bulb roughly corresponded to a certain level of light output.

With LEDs, this no longer applies. Today, you must look at lumens.

As a guideline:

250 lumens ≈ bedside lamp
400–500 lumens ≈ desk lamp
700–800 lumens ≈ hallway or WC
1000–1500 lumens ≈ kitchen, living room, or office

A 6W LED can produce as much light as a 40W incandescent bulb, while consuming up to 7 times less energy.

Standards and visual comfort

In Europe, workplace lighting is regulated by standards such as DIN EN 12464-1, which define the minimum lux levels required depending on the activity. For example, an office requires far more lux than a bedroom.

By considering both lumens (light output) and lux (distribution), you ensure comfort, efficiency, and energy savings.

Lumen tells you how much light your lamp produces, lux tells you how efficiently that light reaches the surface. To optimize your lighting, think about the lamp’s brightness, the surface to be lit, and the type of bulb used.