Mesh to Micron Converter - Free Screen Size Calculator
Convert mesh size to microns and microns to mesh using the ASTM E11 sieve size table. A free calculator for filtration, sieve analysis, and particle sizing.
Mesh to Micron Conversion Tool
Convert mesh sizes to microns with this simple tool.
Based on the ASTM E11 standard sieve opening table
Documentation
Mesh to Micron Converter
A mesh to micron converter turns a sieve's mesh number into the size of its openings in microns, or the other way around. It is used to compare screens and filters that are labeled with different measurement systems.
What is mesh size?
Mesh size is the number of openings per linear inch in a wire screen. A screen with a higher mesh number has more openings packed into that inch, so each opening is smaller. A 20 mesh screen has 20 openings per inch and fairly large gaps. A 200 mesh screen has 200 openings per inch and much finer gaps. Mesh sizes in common use range from about 4 (coarse) to 400 or more (very fine).
What is a micron?
A micron, also called a micrometer, is a unit of length equal to one millionth of a meter. It equals 0.001 millimeters, or about 0.000039 inches. Microns describe the actual width of a screen opening, so they give a more direct measurement of particle size than a mesh number does.
How mesh to micron conversion works
Mesh numbers cannot be turned into micron sizes with one simple formula, because a mesh number only counts openings per inch. It says nothing about how thick the wire between the openings is. Two screens with the same mesh number can have different opening sizes if their wire is a different thickness.
A common shortcut divides 25,400 (the number of microns in one inch) by the mesh number. This gives the spacing between the centers of two wires, not the size of the gap between them. Because the wire itself takes up some of that space, this shortcut makes every opening look far larger than it really is. For a 100 mesh screen, the shortcut gives 254 microns, but the actual opening is closer to 150 microns.
Standards bodies avoid this problem by publishing a table of nominal opening sizes for each mesh number, measured from real screens. The main table used in the United States comes from ASTM E11, a standard maintained by ASTM International. This converter looks up the two mesh numbers in that table closest to the value entered, then estimates a result between them. It does the estimate on a logarithmic scale, because sieve sizes shrink in a curved pattern rather than a straight line as mesh numbers increase. For mesh numbers in the table exactly, the converter returns the table's listed value.
Example calculations
Mesh to micron. A 90 mesh screen sits between 80 mesh (180 microns) and 100 mesh (150 microns) in the ASTM E11 table. The converter estimates its opening at about 163.48 microns, between those two known values.
Micron to mesh. An opening of 100 microns sits between the table's entries for 140 mesh (106 microns) and 170 mesh (90 microns). The converter estimates its mesh number at about 150.02.
Common mesh to micron conversions
These values come directly from the ASTM E11 table, so they match the converter's results exactly.
| Mesh Size | Micron Size | Typical Use |
|---|---|---|
| 20 mesh | 850 microns | Coarse screening, aggregate, gravel |
| 50 mesh | 300 microns | Sand and other granular material |
| 100 mesh | 150 microns | Fine powders, flour-like material |
| 200 mesh | 75 microns | Paint pigment, fine powder work |
| 325 mesh | 45 microns | Pharmaceutical and cosmetic screening |
| 400 mesh | 38 microns | Precision filtration, toner powder |
The table covers mesh numbers from 3.5 (5,600 micron openings) to 635 (20 micron openings). This calculator accepts values outside that range too, extending the same curve past the table's ends, but results there are estimates rather than published standard values.
Uses of mesh and micron measurements
Filtration and screening equipment is often specified in one unit or the other, so converting between them is a routine task. Water treatment plants and chemical processors choose screens by micron rating when they need a specific particle size removed. Sieve analysis in soil testing, pharmaceutical quality control, and materials research reports particle size distributions in microns. Sand, gravel, and ore processing more often use mesh numbers, since that is how screening equipment is traditionally sold and labeled. Paint and pigment manufacturers convert between the two when matching a pigment's particle size to a filter or mill screen.
Frequently asked questions
What is the difference between mesh size and microns? Mesh size counts openings per inch in a screen. Microns measure the actual width of each opening. A higher mesh number means smaller openings and a smaller micron value; for example, 200 mesh (75 microns) has much smaller openings than 50 mesh (300 microns).
Why isn't there one simple formula for this conversion? A mesh number only describes how many openings fit in an inch, not how thick the wire is between them. Two screens with the same mesh number can have slightly different opening sizes depending on wire thickness. Standards bodies solve this by publishing measured opening sizes for each mesh number, which is what this converter looks up instead of using a single formula.
Does this converter work for Tyler mesh sizes? No. This converter uses the US Standard (ASTM E11) mesh series. The Tyler mesh scale, used mainly in older or specialized industrial contexts, is built on a different progression and does not match ASTM numbers one to one.
What is the finest mesh size commonly available? Standard screens typically go up to 400 to 500 mesh, corresponding to about 25 to 38 microns. Finer mesh exists for specialty applications, but it is harder to find and more expensive.
How precise is the converter's result? Results for mesh numbers listed in the ASTM E11 table are exact, taken straight from the standard. Results for numbers between table entries are estimates, calculated by interpolating between the two nearest listed values. All results are rounded to two decimal places.