Magnified schematic — the wire-to-opening ratio is true to scale; very thin lines are drawn at a minimum visible width.
A US standard No. 80 test sieve (ASTM E11) has a nominal opening of 180 µm.
| Opening (microns) | 180 µm |
| Opening (millimeters) | 0.18 mm |
| Opening (inches) | 0.0071 in |
| US standard sieve | No. 80 |
| Tyler equivalent | 80 mesh |
| Pitch (wire center to center) | 305 µm |
| Typical wire diameter | 0.125 mm |
| Approx. open area | 35% |
An 180 µm opening falls within the fine sand (125 µm–250 µm) class of the Wentworth grain-size scale. Comparing grain size with the nominal opening only: very fine sand and finer would pass; medium sand and coarser would be retained; fine sand is split at about 180 µm. Real sieving also depends on particle shape, sieving time and the opening tolerance of the cloth.
These applications commonly use a 80 mesh count or an opening near 180 µm:
24, 50, 80, 100 or 200 mesh
Agricultural nozzle tip strainers are offered with stainless screens of 24, 50, 80, 100 or 200 mesh to keep spray tips from plugging.
Ranges show common practice with sources on the mesh size by application page — always check your equipment maker's recommendation.
The name "80 mesh" suggests 80 openings per inch, i.e. a pitch of 25,400 ÷ 80 = 317.5 µm. Standard test sieves, however, are defined by their opening, not by the count: a 180 µm opening woven with the typical 0.125 mm wire gives a real pitch of 180 + 125 = 305 µm, which is about 83.3 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.
| Mesh | Microns (µm) | Millimeters | Inches |
|---|---|---|---|
| 50 mesh | 300 | 0.3 | 0.0118 |
| 60 mesh | 250 | 0.25 | 0.0098 |
| 70 mesh | 212 | 0.212 | 0.0083 |
| 80 mesh | 180 | 0.18 | 0.0071 |
| 100 mesh | 150 | 0.15 | 0.0059 |
| 120 mesh | 125 | 0.125 | 0.0049 |
| 140 mesh | 106 | 0.106 | 0.0042 |
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.
80 mesh is 180 µm, which is 0.18 mm or 0.0071 inches.
In a simplified comparison with the nominal opening, particles smaller than about 180 µm can pass a 80 mesh screen. An 180 µm opening falls within the fine sand (125 µm–250 µm) class of the Wentworth grain-size scale. Comparing grain size with the nominal opening only: very fine sand and finer would pass; medium sand and coarser would be retained; fine sand is split at about 180 µm. Real sieving also depends on particle shape, sieving time and the opening tolerance of the cloth.
With a typical 0.125 mm wire, 80 mesh has roughly 35% open area. Thicker wire lowers the open area and the opening size.