dots per inch

A close-up of the dots produced by an inkjet printer at draft quality. Actual size is approximately 1⁄4 by 1⁄4 inch (6 by 6 mm). Individual coloured droplets of ink are visible; this sample is about 150 DPI.

Dots per inch (DPI or dpi) is a measure of spatial printing, video or image scanner dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch (25.4 mm). Similarly, dots per millimetre (d/mm or dpmm) refers to the number of individual dots that can be placed within a line of 1 millimetre (0.039 in).