Mesh and Micron Sizes

What is a micron?Micron is the measure of length most frequently used to describe tiny particle size. The term micron is actually a commonly used shorthand for micrometer (American spelling) or micrometre (international spelling). The official symbol for micrometer is μm, sometimes simplified as um. A micrometre is defined as one-millionth of a meter, a little more than one twenty-five thousandth of an inch.

What does mesh size mean?Mesh size is the mesh number (a US measurement standard) and its relationship to the size of the openings in the mesh and thus the size of particles that can pass through these openings. Figuring out the mesh number is simple. All you do is count the number of openings in one linear inch of screen. This count is the mesh number. A 4 mesh screen means there are four little square openings across one inch of screen. A 100 mesh screen has 100 openings per inch, and so on.

Note: As the number indicating the mesh size increases, the size of the openings and thus the size of particles captured decreases. Higher mesh numbers = finer particle sizes. It is very important to remember that mesh size is not a precise measurement of particle size. This is because screens 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. Also, mesh is 2D and the 3D shapes of particles varies dramatically.

How fine do screens get?This depends on the thickness of the wire or strand used to make the mesh. Our screen supplier does not offer any screens finer than 500 mesh. This is because as the mesh number rises, the space between the wires or strands becomes smaller. At some point the mesh number becomes so high that the percentage of open area is too low to be useful. This point is usually somewhere between 450 and 700 mesh depending on the diameter of the wire or filament used.

Note: Beyond 325 to 400 mesh, particle size is normally described only in microns.

Download PDF Mesh & Micron Sizes Chart & E-book

US Mesh* Microns Inches Millimeters
35 500 0.0197 0.5
40 400 0.0165 0.4
45 354 0.0138 0.354
50 297 0.0117 0.297
60 250 0.0098 0.25
70 210 0.0083 0.21
80 177 0.007 0.177
100 149 0.0059 0.149
120 125 0.0049 0.125
140 105 0.0041 0.105
170 88 0.0035 0.088
200 74 0.0029 0.074
230 63 0.0025 0.063
270 53 0.0021 0.053
325 44 0.0017 0.044
400 37 0.0015 0.037
450 32 0.0013 0.032
500 25 0.001 0.025
635 20 0.0008 0.002

*Values are based on the American National Standard for Industrial Wire Cloth (American Standard ASTM - E 11).

Micron Chart showing the different measurements













Download PDF Mesh & Micron Sizes Chart & E-book