When it comes to lighting, several technical factors need to be considered to choose the right spotlight or lamps. Among these, measurement units like lumen and lux play a key role. However, these two photometric units are often confused. Lumeers invites you to discover the difference between these terms, starting with their definitions.
What is a lumen?
Represented by the symbol lm, the lumen is the unit used to quantify the luminous flux of a lighting fixture. It allows you to assess the total amount of light or visible radiation emitted every second by a light source (bulb, lamp, spotlight, etc.).
The lumen, therefore, gives you an idea of the brightness level of a bulb, for example. This value, which is especially relevant for LED bulbs, tells you whether the lighting fixture is low or high in luminous intensity.
The lumen can also be used to measure the amount of light captured by a surface located near a light source of one candela intensity. The candela defines luminous intensity according to a certain direction or angle. It is typically used to assess the brightness of a candle.
What is a lux?
The lux is the unit of measurement that indicates the brightness or lighting intensity in a room, hall, area, etc. With the symbol lx, it represents the amount of light received per unit of area (expressed in square metres).
The lux defines the illumination of a surface that receives a light flux of x lumens per square metre, distributed uniformly. In other words, lux measures the ratio of the number of lumens to the area of the surface lit.
A light source of 500 lumens will light one square metre with 500 lux. It will illuminate a 10-square-metre area with 50 lux. A bulb of 1,000 lumens, shining over a one-square-metre area, will light this space with 1,000 lux.
If those 1,000 lumens are spread over 10 square metres, the surface receives just 100 lux. The fundamental difference between these two units is that lux takes into account the area over which the amount of light (lumen) is distributed.
How many lux and lumens are needed to light a space?
The number of lux required to illuminate a surface depends on how the room is used and its size. For retail spaces like supermarkets and shops, lighting with 450 to 700 lux is generally sufficient.
For living spaces such as the lounge, kitchen worktops, dining room or bedroom, lighting that provides 300 to 500 lux should be suitable. To calculate the number of lumens needed to light these different areas, simply multiply the above values by the area to be illuminated. Lighting for professional settings and indoor workspaces is governed by European standard EN 12464-1, which details all the necessary requirements.
Dining room➞
And if you need to install your lighting fixtures, find out the cost of an electrician.
