Brooks Brothers to Under Armour size
The short answer
Brooks Brothers XS is Under Armour SM by the two brands' own charts. 5 of 6 Brooks Brothers sizes land on a different label at Under Armour.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
| Brooks Brothers | Brooks Brothers builds it for | Under Armour, by chart | Same label | Under Armour builds it for | Under Armour also prints |
|---|---|---|---|---|---|
| XS | chest 34 to 36 in, waist 28 to 30 in, sleeve 32 in | SM | XS | chest 34 to 37 in, waist 29 to 31 in | not published |
| S | chest 36 to 38 in, waist 30 to 32 in, sleeve 33 in | SM | not published | chest 34 to 37 in, waist 29 to 31 in | not published |
| M | chest 38 to 40 in, waist 32 to 34 in, sleeve 35 in | MD | not published | chest 37 to 41 in, waist 31 to 34 in | not published |
| L | chest 42 to 44 in, waist 36 to 38 in, sleeve 36 in | LG | not published | chest 41 to 44 in, waist 34 to 37 in | not published |
| XL | chest 44 to 46 in, waist 40 to 42 in, sleeve 36.5 in | XL | XL | chest 44 to 48 in, waist 37 to 41 in | not published |
| XXL | chest 46 to 48 in, waist 44 to 46 in, sleeve 37 in | XL | XXL | chest 44 to 48 in, waist 37 to 41 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.
- Under Armour size guide, read on 2026-09-18. Under Armour on TrueToSize