The pixel pitch is center to center distance of adjacent pixels measured in millimeters. In a plan term, pixel pitch shows the gap between the pixels of LED display. The smaller pixel pitch means there is smaller empty space between the pixels and there are more number of pixel, results in higher resolution and higher image quality. Figure below illustrate the pixel pitch for a high resolution SMD LED module and standard resolution DIP LED module.

Pixel pitch affect the viewing distance too. The minimum viewing distance is the distance that you can watch image and video with acceptable level of pixilation. The smaller pixel pitch, the smaller gap between the pixel and less pixilation of the image. Therefore, the viewer can stand closer to your display.

To choose the optimum pixel pitch two factors should be considered, the viewing distance and the required image resolution. Smaller pixel pitches are better all the time and deliver you better image quality but, it costs more. You may decrease the expenses of LED display buy using larger pixel pitch and still have almost same image quality if the viewing distance is longer than best viewing distance. The best viewing distance of a pixel pitch is the distance that your eyes won’t be able to the gaps between pixel anymore if you go further away.

Take an LED signs with P10 modules (pixel pitch of 10mm). The minimum viewing distance for P10 is 10m and the best viewing distance is 20m. So, if people watch it from 10m to 50m away, they can see an acceptable image quality with a fading level of pixilation from 10m to 20m and a very good image quality after 20m. So you may want to increase the image quality using P8 or even P6 module for close range. But If the viewing distance was from 20m to 50m, there was no point to use smaller pixel pitch with higher resolution. Because, the viewing distance was already more than best viewing distance of P10.

As a rough estimation, P10 (10mm pixel pitch) is suitable for any outdoor application with viewing distance of 10m and more. P8 or P6 (6mm and 8mm pixel pitch) can also be used if target audience are in closer distance. For indoor applications, P6 may suit any advertising needs with viewing distance of 6m and more. P4 (4mm pixel pitch) can also be used if your audience are closer such as LED video wall in retail environment. For better estimation of pixel pitch you can use the following table.