The amount of lighting needed for a space depends on several parameters: the type of room, the atmosphere you want to create there but also its surface area. Lumens, watts or even kelvins, we are often lost among all these units of measurement. Discover the key elements to finally understand everything, estimate the amount of lighting necessary for the room you want to furnish and make yourself a true lighting specialist!


To illuminate an area of ​​your home effectively while creating a pleasant space to live in on a daily basis, you should learn to master a few lighting concepts. Successful lighting highlights the areas that we want to enhance and highlight, or the living spaces in which we group together and towards which we want to be naturally directed when entering the room: the dining room table , the living room coffee table, the sofa, the kitchen island, etc.

Another data, more subjective this one, also comes into account: the style of arrangement of the room. Indeed, with identical lighting the result will be very different between a refined living room with a light floor and furnished with white wood, and another more busy living room with imposing furniture and a dark floor. Likewise, the lighting power adapts to the activities: work such as homework or meal preparation requires bright lighting while reading or watching television requires rather diffuse and subdued lighting. This element must therefore be taken into account depending on the areas that we wish to develop.

Finally, we are very sensitive to the color of the lighting around us and our mood is largely influenced by the color of light. Cold, direct lighting suggests energy: it is ideal for working times. Warm light is ideal for moments of relaxation: it evokes comfort and calm.


To properly master your lighting, another essential step is to understand and master the technical data.

The essential elements to take into account:

Watts (W)

This unit measures the electrical power produced by the light source, i.e. its electrical consumption. With low-energy bulbs such as LEDs and compact fluorescent bulbs, this unit of measurement no longer reveals the luminous efficiency of a bulb, but its electrical consumption: the higher the number of watts, the more the bulb consumes electricity.

Lumens (lm)

This unit measures the quantity of light emitted by a bulb: this is the luminous flux. This is the decisive criterion for the brightness produced by a bulb, because for the same consumption expressed in watts, not all bulbs produce the same quantity of light. To fully understand, imagine the flow of water coming out of your shower head: the further your hand is from the shower head, the less water it receives or even none at all. In the same way, the further you move your book from your bedside lamp or e-reader, the less light you have to read. Thus, the higher the number of Lumens, the more the bulb produces a significant luminous flux and illuminates efficiently.

Here are some guidelines on the recommended quantity of lumens per living space:

Main lighting for a living room, a dining room, a corridor requires approximately 100 lm/m².

Main lighting for a kitchen or bathroom requires 300 lm/m².

Degrees Kelvin (K)

This unit measures the color temperature of light. Paradoxically, the higher the data, the colder the light, in other words "bluish". And the lower the data, the warmer the light, in other words "orange". Some benchmarks:

Very warm light: orange in appearance / candle flame, around 1500K,
Warm light: orange-yellow in appearance, around 2700 K,
Soft light: neutral white in appearance, around 4000 K,
Cold light: bluish in appearance, closest to daylight, around 6500 K.

Nowadays we mainly find light sources between 2700 and 3000 kelvins on the market: this is the color temperature produced by incandescent bulbs, it is the most neutral and anchored in our uses, neither too hot nor too cold .

Lux (Lx)

Another data must be taken into account because it serves as a basis for calculating the quantity of lighting necessary in a room: these are the Lux (Lx). This unit measures the efficiency of lighting, in other words the flow of light received by an object or surface: this is the luminous illuminance. We calculate it from the lumens emitted by our light sources and the square meters of the surface to be illuminated. To put it simply, one lux corresponds, when the reflection of the support to be illuminated is good, to 1 lumen per m².


The arrangement and characteristics of the light sources that equip your interior must therefore be considered based on 4 criteria:

  • The type of room to be lit,
  • The desired atmosphere,
  • The appropriate light color temperature,
  • The distribution of lighting to take advantage of each space.

Here are some guidelines to guide you in your choices:

Sought-after room and atmosphere

Light intensity

Recommended color

Living room, dining room, adult bedroom. Subdued, intimate atmosphere.

25-50 lux

White hot

Living room, dining room, kitchen, adult bedroom, office. Friendly atmosphere, moments of relaxation.

100-150 lux

White hot

Office, library, child's bedroom, playroom. Work and play atmosphere.

200-250 lux

Neutral white

Technical atmosphere: areas of high activity (office, workshop) and circulation (corridors, entrance)

350-500 lux

White cold


Simplify your life with this quick and simple calculation method: lumens/m² = lux!

Let's take the example of setting up a 15 m² bedroom that would be equipped with 9W low-consumption bulbs which produce 350 lumens.
For a lamp equipped with this bulb and on the basis of the calculation rule cited above, you therefore make the following calculation: 350 lm/15 m² = 23 lux of illumination.

The quantity of Lux produced by a light source must then be multiplied by the number of light points of the same type installed in the room. Thus, with two bedside lamps equipped with this 350 lm bulb, you generate an illuminance of 46 Lux and you place yourself in the recommended range for a bedroom with an intimate atmosphere. If you are looking for a less subdued atmosphere in this room, you will simply have to opt for bulbs producing a greater luminous flux, therefore more Lumens, to increase the lighting accordingly.

Let's start again with the example of a 25 m² living room equipped with 1000 lm LED bulbs: 1000 lm/25 m² = 40 lux of lighting.
This obviously cannot be enough to illuminate the entire room.

How to calculate the number of light points necessary to obtain satisfactory lighting? Well by dividing the recommended light intensity in lux with the lux of illumination produced by the light source. This gives you the number of lamps needed to adequately light your room!
150 lux recommended / 40 lux produced by your LED bulb = 3.75. This is the number of light points to install according to the recommendations in the table. As we need a round number, let's say 4 in this specific case!

Trick :

To be even more specific, divide your living room into different zones and determine the amount of Lux needed to create the desired ambiance in each zone. You are therefore able to work on each space very precisely.

You now have all the elements to decide on your lighting installation depending on the room, the activity and the desired atmosphere!

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