Reiss to Uniqlo clothing size
The short answer
Reiss 4 is Uniqlo S by the two brands' own charts.
Both brands publish the body bust each size is cut for, so every row matches a bust, not a letter or a number.
On 5 sizes the charts land two or more sizes from the same label. Brands do not measure the body the same way, so on those rows treat the chart answer and the same label as the two ends of a range.
| Reiss | Reiss builds it for | Uniqlo Japan sizing, by chart | Same label | Uniqlo builds it for | Uniqlo also prints |
|---|---|---|---|---|---|
| 4 | bust 31 in, waist 24 in, hip 34 in | S | XS | bust 30.3 to 32.7 in, waist 24 to 26.4 in, hip 33.1 to 35.4 in | JP 7 |
| 6 | bust 32 in, waist 25 in, hip 35 in | S | XS | bust 30.3 to 32.7 in, waist 24 to 26.4 in, hip 33.1 to 35.4 in | JP 7 |
| 8 | bust 33 in, waist 26 in, hip 36 in | M | S | bust 31.9 to 34.3 in, waist 25.6 to 28 in, hip 34.7 to 37 in | JP 9 |
| 10 | bust 35 in, waist 28 in, hip 38 in | L | S | bust 33.5 to 35.8 in, waist 27.2 to 29.5 in, hip 36.2 to 38.6 in | JP 11 |
| 12 | bust 37 in, waist 30 in, hip 40 in | XL | M | bust 35.8 to 38.2 in, waist 29.5 to 31.9 in, hip 38.6 to 40.9 in | JP 13 |
| 14 | bust 39 in, waist 31.5 in, hip 42 in | XXL | M | bust 38.2 to 40.6 in, waist 31.9 to 34.3 in, hip 40.9 to 43.3 in | JP 15 |
| 16 | bust 41 in, waist 33.5 in, hip 44 in | 3XL | L | bust 40.6 to 42.9 in, waist 34.3 to 36.6 in, hip 43.3 to 45.7 in | JP 17 |
| 18 | bust 43 in, waist 36 in, hip 46.5 in | 3XL | L | bust 40.6 to 42.9 in, waist 34.3 to 36.6 in, hip 43.3 to 45.7 in | JP 17 |
What wearers say
Charts describe a garment, not a fit. We do not collect fit reports for this category yet, so this table is the two brands' own claims and nothing more.
Sources
- Reiss size guide, read on 2026-09-18.
- Uniqlo Japan sizing size guide, read on 2026-09-25. Uniqlo on TrueToSize