MeshMicron is a free set of tools for converting between mesh sizes, microns and standard sieve numbers. It was built because most mesh to micron charts online are static PDFs, mix up the ASTM and Tyler scales, or ignore wire diameter.
Where the numbers come from
- Nominal openings: the site's reference table records ASTM E11-13 as its original basis. A sieve number is a designation; it is not an exact count of openings per inch.
- Typical wire diameters: reference values used for geometry and open-area illustrations. They are not measured wire diameters or a certificate for a supplied screen.
- Tyler equivalents: the RETSCH international test sieve comparison table. Tyler 150 and 250 correspond here to ASTM No. 140 (106 µm) and No. 230 (63 µm).
- Non-standard mesh counts: calculated as 25,400 ÷ mesh − wire diameter, using an assumed wire diameter interpolated between ASTM E11 sieves (or extrapolated beyond No. 635). These are estimates, not standard values.
- User-entered wire: Wire Mesh uses the diameter you enter. With the field empty, it uses a typical or assumed diameter and labels that basis in the result and copied text.
Reference check and limits
Comparison checked: . Nominal openings and Tyler equivalents for all 33 numbered rows (No. 3½–635) checked against the RETSCH comparison table.
The comparison PDF does not state an ASTM edition or list typical wire diameters. The full dataset has not been revalidated against E11-24; typical wire diameters remain the existing reference values. See ASTM E11-24 on ASTM's official site for the current standard information. MeshMicron is a reference tool, not an ASTM-certified testing service.
Reverse results compare a size with a nominal opening: below, at the limit, or above. Actual sieving also depends on opening tolerances, particle shape and test conditions. The zero-wire upper bound (25,400 ÷ size in µm) assumes no wire thickness and is not a recommended sieve number.
The tools are for reference. For critical filtration or testing work, confirm specifications with your wire cloth or sieve supplier and the current edition of the relevant standard.