Luminance: cd / m² simply explained
When specifying the display brightness of a smartphone, one often finds the unit cd / m2. This describes the luminance of the device. You can find out exactly what the unit means and which values are recommended in this practical tip.
Luminance as a measure of brightness
- The unit cd / m² sets the photometric size cd (abbreviation for candela) in relation to the area of the display, specified in square meters.
- Candela is the unit of measurement for light intensity. The brightness of a smartphone is directly dependent on the light intensity. A candle, for example, has a cd value of 1. A light bulb 60. The higher the candela, the higher the brightness.
- The same applies to cd / m². However, this indication of the luminance relates to a surface and not to a point, as is the case with light intensity. The luminance cd / m² therefore shows how much light is emitted by a fictitious 1-square meter smartphone.
- In summary, one can say that the luminance indicates the surface brightness that the human eye perceives.
- Sometimes the luminance is also given in "Nit". This is used primarily in the United States, but is not part of the standardized SI values.
![](http://hackzl.com/img/hardware/2437/leuchtdichte-cd-m-einfach-erkl-rt.webp)
What luminance is ideal for my smartphone?
- Common models have between 300 and 400 cd / m². Conventional computer screens and LED video walls even only 200 to 300 cd / m².
- In general, it can be said that the luminance for smartphones cannot be high enough. If the display becomes too bright, you can easily make it darker with the brightness slider.
- Luminance is particularly important when using mobile devices in bright sunshine. The high brightness of the environment usually only makes the screen appear black. Smartphones with a high cd / m² number have a clear advantage here. A prime example is the Samsung Galaxy S8, which is easy to use with over 700 cd / m² in summer.