Both “mesh” and “mesh count” refer to the number of openings per linear inch,To determine mesh or mesh count, start from the center of one wire and count the number of openings to a point exactly one linear inch away. Such as, No. 4 mesh (or 4 x 4 mesh) indicates that, in one linear inch, there are four openings. Likewise, a No. 20 mesh (or 20 x 20 mesh) indicates that in one linear inch, there are twenty (20) openings.