Abrasive grit cross-reference
Enter a designation in any of the three sizing systems and see the equivalents, the particle size each standard actually specifies, and the reasons the two numbers do not mean the same thing.
A Chinese W-grade (W28) or a JIS R6001 grit number (#400). A bare number is read as a W-grade first, then as a JIS grit; prefix with W or # to be explicit. The forms 400# and 28 µm are accepted.
Read as GB/T 2481.2 W28
- GB/T 2481.2 grade (as entered)
- W28
- Basic-grain band
- 20 – 28 µm
- Implied D50 (band midpoint)
- ≈ 24 µm
- JIS R6001 equivalent
- #400
- JIS R6001 D50 band
- 28 – 32 µm
The W28 number is the 28 µm upper bound of this band. The lower bound is 20 µm.
Derived here as the arithmetic midpoint of the band. It is not a value either standard states.
W28 and #400 differ by about 20%. The W28 band midpoint is ≈ 24 µm while the specified D50 of the JIS grit it is conventionally cross-referenced to is 30 µm. Both numbers come from the standards; the gap is arithmetic. A cross-reference pairs nominal cuts — it does not make the two designations interchangeable, so name the number you require rather than the grade.
W28 is a band, not a D50. The number in a Chinese W-grade is the upper bound of the basic-grain band — 20 to 28 µm here — not a median. Reading W28 as “28 µm D50” claims a coarser powder than the grade specifies.
The implied D50 is a comparison aid, not a specification value. It is the midpoint of the band, which assumes the distribution is roughly centred. GB/T 2481.2 specifies what fraction of the powder falls inside the band, not a median, so a fully compliant lot skewed coarse sits above this figure. Use it to put quotations on a common footing; do not write it into a specification.
A particle size without a method named is not a result. Sedimentation reports a hydrodynamic equivalent diameter and ISO 13320 laser diffraction reports a light-scattering equivalent diameter. For angular particles the two do not agree, and sedimentation generally reads finer. Two COAs quoting the same D50 by different methods describe different powders.
Paste-ready specification line
Anchored on the JIS D50 band, because JIS R6001 is the only one of the two standards that specifies a median at all. Check the number against what you actually require before sending it.
D50 30 ± 2 µm (≈ JIS R6001 #400) — measured per ISO 13320 laser diffraction, wet dispersionThe same grit number, two particle sizes
Before any cross-reference matters, this does: JIS and FEPA both call a cut “400” and mean D50 figures nearly twice apart. A quotation that names only a grit number cannot be compared with another.
- JIS R6001 #400 — D50
- ≈ 30 µm
- FEPA F400 — D50
- ≈ 16.5 µm
Cross-reference table
Select any designation to load it into the field above.
| Chinese W-grade (GB/T 2481.2) | Basic-grain band | Implied D50 | JIS R6001 | JIS D50 band |
|---|---|---|---|---|
| 28 – 40 µm | ≈ 34 µm | 33 – 37 µm | ||
| 20 – 28 µm | ≈ 24 µm | 28 – 32 µm | ||
| 14 – 20 µm | ≈ 17 µm | 23 – 27 µm | ||
| 10 – 14 µm | ≈ 12 µm | 18.5 – 21.5 µm | ||
| 7 – 10 µm | ≈ 8.5 µm | 8.7 – 10.3 µm | ||
| 5 – 7 µm | ≈ 6 µm | 7.4 – 8.6 µm | ||
| 0.3 – 0.5 µm | ≈ 0.4 µm | No JIS equivalent | — |
Bands and grit correspondences as set out in GB/T 2481.2 and JIS R6001. The implied D50 column is derived here as the band midpoint and is not stated by either standard.