Lumen vs Lux: What Are the Differences and How to Choose?

When it comes to lighting, two terms come up a lot: lumen and lux. While these terms are often used interchangeably, they represent different concepts and are essential to understanding how to choose the right lighting for your specific needs. In this article, we’ll explore the differences between lumen and lux, and walk you through the process of choosing between the two.

Understanding the Terms: Lumen and Lux

Lumen (lm)

Lumen is a unit of measurement of the total amount of light emitted by a light source in all directions. In other words, it measures the total luminous flux. The higher the number of lumens, the more light the light source emits.

• Example : An 800 lumen LED bulb emits more light than a 400 lumen bulb.

Lux (lx)

Lux, on the other hand, is a unit of measurement for illuminance, that is, the amount of light that reaches a given surface. It measures the luminous intensity per unit area (lumens per square meter). Lux is therefore a measure of the perceived brightness in a specific space.

• Example : A room lit by an 800 lumen bulb can have an illumination of 500 lux at a distance of 1 meter from the light source.

Key Differences Between Lumen and Lux

1. Nature of the Measure :

   • Lumen : Measures the total amount of light emitted by a light source.
   • Lux : Measures the amount of light that reaches a given surface.

2. Application :

   • Lumen : Used to compare the light output of different light sources.
   • Lux : Used to determine the perceived brightness in a specific space.

3. Context of Use :

   • Lumen : Important to choose bulbs or light fixtures based on their ability to emit light.
   • Lux : Important for planning the lighting of a space according to specific needs, such as reading, working or relaxing.

How to Choose Between Lumen and Lux?

When choosing between lumen and lux, it’s essential to understand your specific lighting needs. Here are some steps to help you make the right choice:

1. Determine the Lighting Objective :

   • Lumen : If your goal is to choose a bulb or light fixture based on its ability to emit light, focus on lumens. For example, to replace a 60-watt incandescent bulb, you might look for an 800-lumen LED bulb.
   • Lux : If your goal is to plan the lighting of a space based on perceived brightness, focus on lux. For example, for an office, you might aim for 500 lux to ensure good visibility for work.

2. Measuring Space :

   • Lumen : No need to measure the space, as you focus on the total amount of light emitted by the source.
   • Lux : Measure the area of ​​the space you want to illuminate to determine the required illuminance. Use the following formula to calculate lux:$$\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">Lux</span></span></span>}<span\; class="katex-display"\; data-mce-fragment="1"><span\; class="katex"\; data-mce-fragment="1"><span\; class="katex-mathml"\; data-mce-fragment="1">=</span></span></span>\frac{\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">Lumens</span></span></span>}}{\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">Surface area (in m</span></span></span>}\stackrel{<span\; class="katex-display"\; data-mce-fragment="1"><span\; class="katex"\; data-mce-fragment="1"><span\; class="katex-mathml"\; data-mce-fragment="1">ˋ</span></span></span>}{\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">e</span></span></span>}}\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">very square</span></span></span>}\stackrel{<span\; class="katex-display"\; data-mce-fragment="1"><span\; class="katex"\; data-mce-fragment="1"><span\; class="katex-mathml"\; data-mce-fragment="1">ˊ</span></span></span>}{\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">e</span></span></span>}}\text{<span class="katex-display" data-mce-fragment="1"><span class="katex" data-mce-fragment="1"><span class="katex-mathml" data-mce-fragment="1">s)</span></span></span>}}$$Lux = Surface area (in m e ˋ very square e ˊ s) Lumens

3. Consider Specific Needs :

   • Lumen : Choose bulbs or fixtures with a lumen rating that suits your needs. For example, for general lighting in a medium-sized room, a bulb with 800 to 1600 lumens may be sufficient.
   • Lux : Determine the illumination needed for different activities. For example, for reading, 300 to 500 lux is recommended, while for specific tasks such as sewing or drawing, 1000 lux or more may be necessary.

Practical Examples

1. General Lighting of a Room :

   • Lumen : To light a room of 20 square meters, you can choose a 1600 lumen bulb.
   • Lux : To obtain an illuminance of 200 lux in a room of 20 square meters, you will need a light source emitting 4000 lumens (200 lux * 20 square meters).

2. Office Lighting :

   • Lumen : For an office, you can choose a desk lamp emitting 800 lumens.
   • Lux : To obtain an illuminance of 500 lux on a work surface of 1 square meter, you will need a light source emitting 500 lumens (500 lux * 1 square meter).

3. Kitchen Lighting :

   • Lumen : To light a 15 square meter kitchen, you can choose a 1200 lumen bulb.
   • Lux : To obtain an illumination of 300 lux in a kitchen of 15 square meters, you will need a light source emitting 4500 lumens (300 lux * 15 square meters).

Tips for Optimal Lighting

1. Combine Lumen and Lux : For optimal lighting, it is often useful to combine the two measurements. Choose bulbs with a number of lumens that suits your needs, then adjust their positioning to obtain the desired illuminance in lux.
2. Use Suitable Lighting Fixtures : Choose lighting fixtures that direct light where it is needed. For example, ceiling lights for general lighting and desk lamps for targeted lighting.
3. Consider the Reflection of Light : Light, reflective surfaces can increase perceived illuminance, while dark, absorbent surfaces can reduce it.
4. Adjust Brightness : Use dimmable bulbs to adjust the brightness according to your needs and the time of day.

Lumen vs Lux: Practical Applications

To better understand the practical application of lumens and lux, let's look at some common scenarios:

1. Living Room Lighting :

   • Objective : Create a warm and welcoming atmosphere.
   • Lumen : Choose bulbs from 800 to 1600 lumens for general lighting.
   • Lux : Aim for 100 to 200 lux of illumination for a comfortable atmosphere.
   • Advice : Use light fixtures with lampshades to diffuse the light and create a soft atmosphere.

2. Bathroom Lighting :

   • Objective : Ensure good visibility for daily activities such as shaving or applying makeup.
   • Lumen : Choose bulbs from 800 to 1200 lumens for general lighting.
   • Lux : Aim for 300 to 500 lux illumination around the mirror for good visibility.
   • Advice : Use wall sconces or recessed spotlights for targeted, shadow-free lighting.

3. Bedroom Lighting :

   • Objective : Create a relaxing atmosphere for sleep and relaxation.
   • Lumen : Choose bulbs from 400 to 800 lumens for general lighting.
   • Lux : Aim for 50 to 100 lux of illumination for a calming atmosphere.
   • Advice : Use bedside lamps with dimmable bulbs to adjust the brightness to suit your needs.

4. Home Office Lighting :

   • Objective : Ensure good visibility for work and reading.
   • Lumen : Choose bulbs from 800 to 1200 lumens for general lighting.
   • Lux : Aim for 500 to 700 lux of illumination on the work surface for good visibility.
   • Advice : Use adjustable desk lamps to adjust the brightness and direction of light according to your needs.

5. Kitchen Lighting :

   • Objective : Ensure good visibility for meal preparation and cooking activities.
   • Lumen : Choose bulbs from 1200 to 1600 lumens for general lighting.
   • Lux : Aim for illumination of 300 to 500 lux for good visibility.
   • Advice : Use recessed spotlights or pendants for targeted, shadow-free lighting.

Modern Technologies and Innovations

With the advancement of technology, new innovations in lighting are constantly emerging. Here are some modern technologies that may influence your choice between lumen and lux:

1. Smart LED Bulbs :

   • Description : Smart LED bulbs come with advanced features like Wi-Fi, Bluetooth or Zigbee connectivity, allowing remote control via mobile apps or voice assistants.
   • Benefits :
     • Remote Control : You can turn on, turn off, adjust brightness and change color of the light remotely.
     • Automation : Smart bulbs can be programmed to turn on and off at specific times, or in response to motion sensors.
     • Home Automation Integration : They can be integrated into home automation systems for centralized lighting management.
   • Disadvantages :
     • Initial Cost : Smart bulbs are generally more expensive than standard LED bulbs.
     • Complexity : Setting up and using smart bulbs can be more complex, requiring some familiarity with the technology.

2. RGB LED bulbs :

   • Description : RGB (Red, Green, Blue) LED bulbs allow you to change the color of the light by mixing different intensities of red, green and blue.
   • Benefits :
     • Versatility : You can create different atmospheres according to your needs and mood.
     • Personalization : RGB LED bulbs offer a wide range of colors to customize your lighting.
   • Disadvantages :
     • Cost : RGB LED bulbs can be more expensive than standard LED bulbs.
     • Complexity : Setting up and using RGB LED bulbs can be more complex.

3. Dimmable LED Bulbs :

   • Description : Dimmable LED bulbs allow you to adjust the brightness according to your needs.
   • Benefits :
     • Flexibility : You can adjust the brightness for different activities, such as reading, working or relaxing.
     • Energy Saving : By reducing the brightness, you can save energy.
   • Disadvantages :
     • Cost : Dimmable LED bulbs can be more expensive than standard LED bulbs.
     • Compatibility : Make sure the dimmable LED bulbs are compatible with your dimmer switch.

Understanding the difference between lumen and lux is essential to choosing the right lighting for your specific needs. By considering the total amount of light emitted by a source (lumen) and the perceived brightness in a given space (lux), you can create a well-lit and comfortable environment.

Remember to consider your specific lighting needs, measure the space, and choose the right lighting fixtures to achieve optimal lighting. By following the tips in this article, you will be well equipped to make the right choice between lumen and lux and improve your home or business lighting.