What are nits?
Essentially, nits are a measure of brightness. Of course, there’s more:
A nit is a unit of a display’s luminance. The SI unit is the candela per square meter (cd/m2). One nit is one cd/m2.
A candela is the SI unit for luminous intensity and one candela approximately equals the intensity of light emitted from one normal candle. That means a display with a luminance of 300 nits is about as bright as if you packed 300 candles into a square meter.
What is a good nit rating?
What can be considered a good nit rating depends heavily on how the display will be used and other features of the selected display.
Many LCDs for indoor use are between 200 and 300 nits. To set some understanding of how bright we’re talking about, the max brightness on a phone in 2020 tends to be between 500 and 700 nits. Typically, anything over 500 nits is considered sunlight readable. Of course, many other factors contribute to whether a display is sunlight readable (reflective or transflective polarizers, Blanview technology, etc.), but at around 500 nits, the backlight can overpower the sunlight to make the display readable. For more, read our blog post on what makes a display sunlight readable.
Just like with your phone, a higher brightness display requires more power. A lower nit display with physical shading may be a better choice for some applications than a higher nit display. Further, just like with your phone, high brightness can be extremely unpleasant in dark environments. As such, when determining whether a nit rating is “good,” consider the application of the display.
Additionally, remember that the luminance rating is often determined based on the backlight without the LCD panel installed. This means the apparent brightness is going to be significantly lower than the brightness listed in the datasheet.
What is the difference between nits and lumens?
Nits and lumens measure different characteristics about how light is emitted. Lumens measure luminous flux, also known as the total light output in all directions. Nits measure luminance, which quantifies directional light.
For further information, check out this nice poster illustrating different terms about light (the second page) created by Radiant Vision Systems.