"Pixel pitch" is "the distance between pixels." In the case of an LCD the pixels are right up against each other so you can also think of it as "the size of a pixel." The higher the pixel pitch, the bigger an image is displayed.
For example, if one square in the diagrams below equals one pixel, the diagram on the left shows a monitor with a high pixel pitch and the one on the right shows a monitor with a low pixel pitch. The same image of an arrow is being displayed with the same number of pixels but the image is bigger on the left-hand monitor with the higher pixel pitch. In other words, when data is displayed from the same computer, the appearance (size) of the letters will vary according to the pixel pitch.
When you think about it, letters will look smaller on a large monitor with a low pixel pitch than on a small monitor with a high pixel pitch.
- The difference between pixel pitches (diagram)

A high pixel pitch
A low pixel pitch


