Free Mesh to Micron Converter

The mesh to micron converter (often referred to as a mesh to microns calculator or particle size mesh converter) is a free online tool that translates sieve mesh numbers into their corresponding particle sizes in microns. Whether you need to evaluate a powder’s fineness, check a filter’s rating, or compare granulometry data, this converter relies on established ASTM mesh to micron tables and a simple rule of thumb to deliver reliable results. Below we explore the concept of mesh, the challenges of direct conversion, and how to use the tool for accurate particle size analysis.

What Is Mesh in Particle Sizing?

In granular material measurement, mesh is a unit that indicates the number of openings per linear inch in a sieve screen. For instance, a 100‑mesh sieve contains 100 openings per inch, meaning the openings are relatively fine, while a 3‑mesh sieve has only three openings per inch, producing much larger apertures. The term originates from the physical sieve itself: particles smaller than the openings fall through, and larger ones are retained. By monitoring what passes through and what stays behind, analysts can characterize the size distribution of powders, grains, and other particulates.

Understanding Mesh Size

The mesh number is simply the count of openings in one inch of screen. A higher mesh number corresponds to more openings per inch and therefore smaller openings. This inverse relationship extends to particle retention: a 200‑mesh screen catches particles that a 100‑mesh screen would let through. However, because the wire thickness used to weave the sieve can vary, two sieves with the same mesh number may have slightly different opening widths. This is why a universal, one‑to‑one conversion from mesh to a linear unit like microns does not exist — yet practical approximations are available.

Why Direct Mesh-to‑Micron Conversion Isn’t Simple

If a single conversion factor could be applied, converting mesh to microns would be trivial. In reality, the opening width depends not only on the number of openings per inch but also on the diameter of the wire. A sieve made with thicker wire will have narrower openings for the same mesh count, and vice versa. Consequently, no official formula works for all sieves. However, the American Society for Testing and Materials (ASTM) has published standardized tables that pair mesh numbers with approximate micron values, which are widely adopted in industry and quality control.

Approximate Formula for Quick Conversion

For mesh numbers between 50 and 400, a rough rule of thumb can be used:

$$\text{Microns} \approx \frac{14,900}{\text{Mesh}}$$

Conversely, to estimate the mesh from a micron value:

$$\text{Mesh} \approx \frac{14,900}{\text{Microns}}$$

Keep in mind that these formulas give a ballpark figure; for critical applications always refer to an official ASTM mesh to micron conversion table.

ASTM Mesh to Micron Conversion Table (Selected Values)

The table below lists common US standard mesh sizes and their corresponding micron openings according to ASTM guidelines:

Mesh (US Std.)	Particle Size (µm)
3	6730
4	4760
5	4000
6	3360
7	2830
8	2380
10	2000
12	1680
14	1410
16	1190
18	1000
20	841
25	707
30	595
35	500
40	400
45	354
50	297
60	250
70	210
80	177
100	149
200	74
400	37

Use this chart as a quick reference when you need to convert mesh numbers to microns without running an online tool.

How to Use the Mesh to Micron Converter

Operating this free mesh to micron converter is straightforward:

1. Select the mesh number from the dropdown menu (or type it in if the input field is provided).
2. The tool immediately displays the corresponding micron value based on the ASTM standard and the approximate formula.
3. For reverse conversions (microns to mesh), enter the micron value and the converter will show the closest mesh size.

The calculator also shows the opening width in inches and millimeters for reference, making it a versatile aid for engineers, lab technicians, and anyone involved in particle size analysis.