Mesh to Micron Conversion Chart


U.S. MESH INCHES MICRONS MILLIMETERS
3 0.265 6730 6.73
4 0.187 4760 4.76
5 0.157 4000 4
6 0.132 3360 3.36
7 0.111 2830 2.83
8 0.0937 2380 2.38
10 0.0787 2000 2
12 0.0661 1680 1.68
14 0.0555 1410 1.41
16 0.0469 1190 1.19
18 0.0394 1000 1
20 0.0331 841 0.841
25 0.028 707 0.707
30 0.0232 0.595 0.595
35 0.0197 500 0.5
40 0.0165 400 0.4
45 0.0138 354 0.354
50 0.0117 297 0.297
60 0.0098 250 0.25
70 0.0083 210 0.21
80 0.007 177 0.177
100 0.0059 149 0.149
120 0.0049 125 0.125
140 0.0041 105 0.105
170 0.0035 88 0.088
200 0.0029 74 0.074
230 0.0024 63 0.063
270 0.0021 53 0.053
325 0.0017 44 0.044
400 0.0015 37 0.037
SIEVE MESH# INCHES MICRONS TYPICAL MATERIAL
14 0.0555 1400 -
28 0.028 700 Beach Sand
60 0.0098 250 Fine Sand
100 0.0059 150 -
200 0.0029 74 Portland Cement
325 0.0017 44 Silt
400 0.0015 37 Plant Pollen
-1200 0.0005 12 Red Blood Cell
-2400 .0002 6 -
-4800 0.0001 2 Cigarette Smoke

The mesh numbers in parentheses are too small to exist as actual screen sizes; they are estimates included for reference. 

Mesh Sizes and Microns

What does mesh size mean?
Figuring out mesh sizes is simple. All you do is count the number of openings in one inch of screen (in the United States, anyway.) The number of openings is the mesh size. So a 4-mesh screen means there are four little squares across on e linear inch of screen. A 100-mesh screen has 100 openings, and so on. As the number describing the mesh size increases, the size of the particles decreases. Higher numbers equal finer material. Mesh size is not a precise measurement of particle size.

What do the minus (-) and plus (+) signs mean when describing mesh sizes?
Here's a simple example of how they work. -200 mesh would mean that all particles smaller than -200 mesh would pass through. +200 mesh means that all the particles 200-mesh or larger are retained.

How fine do screens get?
That depends on the wire thickness. If you think about it, the finer the weave, the closer the wires get together, eventually leaving no space between them at all. For this reason, beyond 325-mesh particle size is usually described in "microns".

What is a micron?
A micron is another measurement of particle size. A micron is one-millionth of a meter or one twenty-five thousandth of an inch.