In the above table, these values are generally accepted as accurate but are approximates, because when the mesh count is constant and the wire diameter changes, the aperture will change accordingly. For Example: 200 mesh to micron is 74micron, 325 mesh to micron is 44 micron, 120 micron mesh is about 120 mesh, 100 micron filter is about 140 mesh.
What is Mesh Size?
Number of openings in a linear inch measured from the center of one wire to a point 1" distant.
Since the size of screen (one square inch) is constant, the higher the mesh number the smaller the screen opening and the smaller the particle that will pass through.
Wire mesh can be made with different materials with different thicknesses of strands or wire. The thicker the strands, the smaller the openings that a particle can pass through, and vice versa.
What is a micron?
The official symbol for the micron or micrometer is μm. A micron is defined as one-millionth of a meter, a little more than one twenty-five thousandth of an inch.
Mesh count=25.4mm/(wire diameter+aperture).
Aperture(mm)=25.4mm/mesh count-wire diameter(mm).