Quick answer
400 mesh ≈ 37 µm
According to common US sieve references, 400 mesh correlates with about 37 micrometers (0.037 mm / 0.0015 in). Validate critical specs independently.
Reference opening
- Mesh
- 400
- Millimeters (mm)
- 0.037
- Microns (µm)
- 37
- inch
- 0.0015
Ultra-fine polishing
Approximate sieve opening — not a formula
Mesh counts describe weave density; micron columns summarize nominal aperture sizes taken from ASTM-like charts. Wire diameter tolerances, corrosion, ISO vs ASTM wording, and microscope calibration all influence measured openings.
Nearby mesh comparison
| Mesh | µm | mm | Link |
|---|---|---|---|
| 400 | 37 | 0.037 | Mesh detail page |
| 325 | 44 | 0.044 | Mesh detail page |
| 500 | 25 | 0.025 | Mesh detail page |
Try the live calculators
Jump into the interactive tools when you need arbitrary mesh counts, micron targets, or quick copy/paste summaries for RFQs.
How industrial teams interpret this row
Treat handbook micron openings as communication shorthand — procurement still requires supplier certs; QA needs retained-mass logs tied to calibrated stacks.
Typical applications
Teams deploy these meshes across powder coatings, pharmaceutical milling, hydraulic filtration, abrasive blasting, and precision polishing workflows.
People also ask
- Is 400 mesh finer than 325 mesh?
- Higher mesh counts mean smaller openings — compare micron columns when unsure.
- Can I buy exact micron cloth?
- Most vendors quote mesh counts — convert using standardized charts then confirm measurements.
- Does humidity affect sieve tests?
- Yes — hygroscopic powders cake and skew retained masses.
- Which ASTM or ISO doc applies?
- ASTM E11 governs many North American test sieves while ISO 3310-1 covers woven wire internationally — cite whichever your PO references.
- Why trust MeshToMicron.org?
- We expose transparent handbook rows plus disclaimers — always reconcile against your supplier calibration packet.
Values remain approximate — cite supplier certifications when auditing.