Under Armour to Nike size
The short answer
Under Armour SM is Nike S by the two brands' own charts. 5 of 9 Under Armour sizes land on a different label at Nike.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
| Under Armour | Under Armour builds it for | Nike, by chart | Same label | Nike builds it for | Nike also prints |
|---|---|---|---|---|---|
| XS | chest 31 to 34 in, waist 28 to 29 in | XS | XS | chest 31.5 to 35 in, waist 25.5 to 29 in, hip 31.5 to 35 in | not published |
| SM | chest 34 to 37 in, waist 29 to 31 in | S | not published | chest 35 to 37.5 in, waist 29 to 32 in, hip 35 to 37.5 in | not published |
| MD | chest 37 to 41 in, waist 31 to 34 in | M | not published | chest 37.5 to 41 in, waist 32 to 35 in, hip 37.5 to 41 in | not published |
| LG | chest 41 to 44 in, waist 34 to 37 in | L | not published | chest 41 to 44 in, waist 35 to 38 in, hip 41 to 44 in | not published |
| XL | chest 44 to 48 in, waist 37 to 41 in | XL | XL | chest 44 to 48.5 in, waist 38 to 43 in, hip 44 to 47 in | not published |
| XXL | chest 48 to 52 in, waist 41 to 45.5 in | XXL | XXL | chest 48.5 to 53.5 in, waist 43 to 47.5 in, hip 47 to 50.5 in | not published |
| 3XL | chest 52 to 56 in, waist 45.5 to 50 in | 3XL | 3XL | chest 53.5 to 58 in, waist 47.5 to 52.5 in, hip 50.5 to 53.5 in | not published |
| 4XL | chest 56 to 60 in, waist 50 to 54.5 in | 3XL | 4XL | chest 53.5 to 58 in, waist 47.5 to 52.5 in, hip 50.5 to 53.5 in | not published |
| 5XL | chest 60 to 64 in, waist 54.5 to 59 in | 4XL | not published | chest 58 to 63 in, waist 52.5 to 57 in, hip 53.5 to 58.5 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
- Under Armour size guide, read on 2026-09-18. Under Armour on TrueToSize
- Nike size guide, read on 2026-09-18. Nike on TrueToSize