Brooks Brothers to GU size
The short answer
Brooks Brothers XS is GU M by the two brands' own charts. 5 of 6 Brooks Brothers sizes land on a different label at GU.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
On 1 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.
| Brooks Brothers | Brooks Brothers builds it for | GU Japan sizing, by chart | Same label | GU builds it for | GU also prints |
|---|---|---|---|---|---|
| XS | chest 34 to 36 in, waist 28 to 30 in, sleeve 32 in | M | XS | chest 34.7 to 37.8 in, waist 29.9 to 33.1 in | not published |
| S | chest 36 to 38 in, waist 30 to 32 in, sleeve 33 in | M | S | chest 34.7 to 37.8 in, waist 29.9 to 33.1 in | not published |
| M | chest 38 to 40 in, waist 32 to 34 in, sleeve 35 in | L | M | chest 37.8 to 40.9 in, waist 33.1 to 36.2 in | not published |
| L | chest 42 to 44 in, waist 36 to 38 in, sleeve 36 in | XL | L | chest 40.9 to 44.1 in, waist 36.2 to 39.4 in | not published |
| XL | chest 44 to 46 in, waist 40 to 42 in, sleeve 36.5 in | XXL | XL | chest 44.1 to 47.2 in, waist 39.4 to 42.5 in | not published |
| XXL | chest 46 to 48 in, waist 44 to 46 in, sleeve 37 in | XXL | XXL | chest 44.1 to 47.2 in, waist 39.4 to 42.5 in | not published |
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
- Brooks Brothers size guide, read on 2026-09-18.
- GU Japan sizing size guide, read on 2026-09-25.