Convert between US/Tyler sieve mesh numbers and micron openings using ASTM E11, with particle-size classification and a sub-sieve milling reference.
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The ASTM E11 standard specifies 45 µm for a 325-mesh sieve. The Tyler series gives 43 µm. Many older references cite 44 µm (a rounded average). When your protocol specifies 325 mesh, confirm which standard it follows — the 2 µm difference can matter for fine-powder specifications.
Higher mesh number = finer opening = smaller particles passing through. A 325-mesh sieve is much finer than a 100-mesh sieve (150 µm). This is counterintuitive to users new to sieve notation. The mesh number counts wires per linear inch, so more wires = smaller gaps.
A sieve pass/retain result tells you the fraction of particles above or below a single cut size. It does not give you a distribution (D10/D50/D90). For specification work requiring a full distribution, combine sieve analysis with laser diffraction or sedimentation.
If your target is below ~44 µm (325 mesh), wire-cloth sieves cannot make the cut. Planetary ball milling is the standard laboratory route to the sub-sieve range, reaching 0.1 µm with the right media and cycle. The size-spectrum ruler in this tool shows exactly where sieving stops and milling takes over.
Mesh → micron uses an exact lookup against the ASTM E11 or Tyler table; off-table mesh numbers use log-linear interpolation between the two nearest bracketing points: where . Micron → mesh applies the inverse on the same table. The nearest standard sieve is found by minimizing . Classification bands: Coarse > 2000 µm; Medium 250–2000 µm; Fine 44–250 µm; Very fine 10–44 µm; Ultrafine / sub-sieve < 10 µm.
Last validated 2026-06-14. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience Mesh to Micron Converter (v1.0.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/mesh-to-micron-converter
ASTM International. ASTM E11: Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves. ASTM International; 2022.
Allen T. Particle Size Measurement, 5th ed. Chapman & Hall; 1997.
International Organization for Standardization. ISO 565: Test Sieves — Metal Wire Cloth, Perforated Metal Plate and Electroformed Sheet. ISO; 2020.
Two sieve series are in common use in North American and international laboratories.
Maintained by ASTM International and harmonized with ISO 565/3310-1. Openings are specified in millimeters (or micrometers for fine sieves) rather than mesh count, but mesh numbers are widely used informally. Regulatory filings in the US (USP, ASTM methods, EPA methods) reference ASTM E11. Key reference points: 200 mesh = 75 µm, 325 mesh = 45 µm, 400 mesh = 38 µm, 500 mesh = 25 µm, 635 mesh = 20 µm.
An older industrial standard historically used in mining, geology, and comminution. Tyler mesh numbers are close but not identical to ASTM for many sizes. Key Tyler points: 200 mesh = 74 µm, 270 mesh = 53 µm, 325 mesh = 43 µm, 400 mesh = 38 µm. When reading legacy protocols or published particle-size data, confirm which standard was used.
For coarse sieves (< 100 mesh) the two series diverge substantially in mesh number for the same opening. For finer sieves the nominal openings are close but differences of 2–5 µm are significant when targeting 44 µm (325 mesh) specification tolerances.
Between tabulated standard points, opening and mesh number follow an approximately geometric (log-linear) relationship. This converter uses log-space interpolation to estimate openings for non-standard mesh numbers, which gives more accurate results than linear interpolation across a series that spans nearly 5 orders of magnitude (0.1 µm to 25 mm).
Particle size affects virtually every downstream measurement: extraction efficiency, dissolution rate, spectroscopic signal, chromatographic resolution, and immunoassay homogeneity. Understanding where your target size falls in the broader spectrum helps you choose the right method.
Standard wire-cloth sieves are practical down to approximately 20–38 µm (ASTM 635–400 mesh). Below that, particles bridge the mesh, electrostatic forces dominate gravity, and separations become unreliable. Planetary ball milling extends the practical range from the coarse sieve floor down to approximately 0.1 µm for hard brittle materials — roughly 3.5 decades below where sieving stops.
Report the measurement method alongside the size value — D50 by laser diffraction and sieve-pass size are not interchangeable.
When your target size falls in the Very fine (10–44 µm) or Ultrafine/sub-sieve (< 10 µm) band, sieving cannot be used to confirm the result. Planetary ball milling to the target size followed by laser diffraction is the standard analytical sample-prep workflow. The BKBM-V2S reaches 0.1 µm minimum output with appropriate media and cycle time.
