01 — StandardWhat is 250 mesh in microns?
250 mesh is a Tyler designation. It matches the US standard No. 230 sieve (ASTM E11), with a nominal opening of 63 µm.
02 — Specifications250 mesh specifications
| Opening (microns) | 63 µm |
| Opening (millimeters) | 0.063 mm |
| Opening (inches) | 0.0025 in |
| US standard sieve | ≈ No. 230 |
| Tyler equivalent | 250 mesh |
| Pitch (wire center to center) | 108 µm |
| Typical wire diameter | 0.045 mm |
| Approx. open area | 34% |
03 — ApplicationsWhat is 250 mesh used for?
A 63 µm opening falls within the very fine sand (62.5 µm–125 µm) class of the Wentworth grain-size scale. Comparing grain size with the nominal opening only: silt and finer would pass; fine sand and coarser would be retained; very fine sand is split at about 63 µm. Real sieving also depends on particle shape, sieving time and the opening tolerance of the cloth.
We have no sourced application data for openings this size yet.
Ranges show common practice with sources on the mesh size by application page — always check your equipment maker's recommendation.
04 — CalculationHow the 250 mesh value is calculated
The name "250 mesh" suggests 250 openings per inch, i.e. a pitch of 25,400 ÷ 250 = 101.6 µm. Standard test sieves, however, are defined by their opening, not by the count: a 63 µm opening woven with the typical 0.045 mm wire gives a real pitch of 63 + 45 = 108 µm, which is about 235.2 wires per inch. That is why mesh numbers and micron values never line up perfectly — and why this site uses the ASTM E11 opening as the answer.
05 — CompareNearby mesh sizes
| Mesh | Microns (µm) | Millimeters | Inches |
|---|---|---|---|
| 170 mesh | 90 | 0.09 | 0.0035 |
| 200 mesh | 75 | 0.075 | 0.003 |
| 230 mesh | 63 | 0.063 | 0.0025 |
| 250 mesh | 63 | 0.063 | 0.0025 |
| 270 mesh | 53 | 0.053 | 0.0021 |
| 300 mesh | ≈ 51 | 0.051 | 0.002 |
| 325 mesh | 45 | 0.045 | 0.0018 |
Values are ASTM E11 nominal openings (Tyler equivalents for 150 and 250 mesh). Italic ≈ values are estimates for non-standard mesh counts, calculated from the mesh count and an assumed wire diameter (interpolated between ASTM E11 sieves, or extrapolated beyond No. 635). Wire values are ASTM E11 typical wire for standard sizes.
06 — FAQFrequently asked questions
How many microns is 250 mesh?
250 mesh is 63 µm, which is 0.063 mm or 0.0025 inches.
What size particles pass through a 250 mesh screen?
In a simplified comparison with the nominal opening, particles smaller than about 63 µm can pass a 250 mesh screen. A 63 µm opening falls within the very fine sand (62.5 µm–125 µm) class of the Wentworth grain-size scale. Comparing grain size with the nominal opening only: silt and finer would pass; fine sand and coarser would be retained; very fine sand is split at about 63 µm. Real sieving also depends on particle shape, sieving time and the opening tolerance of the cloth.
What is the open area of 250 mesh?
With a typical 0.045 mm wire, 250 mesh has roughly 34% open area. Thicker wire lowers the open area and the opening size.