Calculation formula of mesh number of screen
Mesh size refers to the number of holes arranged in a length of one inch (25.4mm), that is, the number of mesh. It's not 25.4mm2, it's in this length column. For example, if the total length of the two holes on the far left is 25.4, then it is two eyes, not four eyes.
The mesh number is n, the wire diameter is D and the aperture is r.
Mesh n = 25.4 / (D + R)
Aperture r = 25.4/n-d