What is Mesh?
What is Micron?
Micron also called um is a length unit which is 0.001mm or 0.00003937inch, usually to describe the tiny particles size, and aperture size of the mesh fabric in industrial filtration. The Micron size of mesh should be smaller than the particle size in the fluid to capture them.
The relationship between Mesh and Micron
The higher mesh count means there are more holes and wire density in unit length, so the micron of aperture decreasing. But they are not fixed proportion as the different mesh count has different yarn diameter (thickness).

How to calculate the Aperture Micron (Mesh Opening)?
M=Mesh Count
R=Yarn diameter (mm)
A=Aperture
Aperture=25.4/(divided)Mesh Count-Yarn Diameter
For example: 100mesh count with thread diameter 0.1mm (100um), its aperture (mesh opening) is 25.4/100 – 0.1=0.154mm (154um).
200mesh count with thread diameter 0.05mm(50um), its aperture (mesh opening) is 25.4/200-0.05=0.077 mm(77um)
Mesh VS Micron Chart (Nylon & Polyester general)
Mesh Count | Mesh Opening | |||
mesh/inch | mesh/cm | Micron | mm | inch |
12 | 5 | 1566 | 1.566 | 0.0617 |
16 | 6 | 1188 | 1.188 | 0.0467 |
18 | 7 | 1061 | 1.061 | 0.0418 |
20 | 8 | 920 | 0.920 | 0.0362 |
24 | 9 | 808 | 0.808 | 0.0318 |
25 | 10 | 766 | 0.766 | 0.0302 |
30 | 12 | 547 | 0.547 | 0.0215 |
35 | 14 | 476 | 0.476 | 0.0187 |
40 | 16 | 435 | 0.435 | 0.0171 |
50 | 20 | 308 | 0.308 | 0.0121 |
60 | 24 | 273 | 0.273 | 0.0107 |
70 | 28 | 212 | 0.212 | 0.0083 |
80 | 32 | 217 | 0.217 | 0.0085 |
90 | 36 | 182 | 0.182 | 0.0072 |
100 | 40 | 154 | 0.154 | 0.0061 |
110 | 43 | 174 | 0.174 | 0.0069 |
120 | 48 | 132 | 0.132 | 0.0051 |
140 | 56 | 121 | 0.121 | 0.0048 |
150 | 59 | 109 | 0.109 | 0.0043 |
160 | 64 | 99 | 0.099 | 0.0039 |
180 | 72 | 91 | 0.091 | 0.0036 |
200 | 80 | 77 | 0.077 | 0.0030 |
230 | 90 | 70 | 0.070 | 0.0028 |
250 | 100 | 62 | 0.062 | 0.0024 |
280 | 110 | 51 | 0.051 | 0.0020 |
305 | 120 | 43 | 0.043 | 0.00169 |
330 | 130 | 37 | 0.037 | 0.00145 |
355 | 140 | 35 | 0.035 | 0.00137 |
400 | 157 | 25 | 0.025 | 0.00098 |
430 | 169 | 20 | 0.020 | 0.00078 |
470 | 185 | 15 | 0.015 | 0.00059 |
530 | 208 | 9 | 0.009 | 0.00035 |