Under Armour to lululemon size
The short answer
Under Armour SM is lululemon XS by the two brands' own charts. 7 of 8 Under Armour sizes land on a different label at lululemon.
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 | lululemon, by chart | Same label | lululemon builds it for | lululemon also prints |
|---|---|---|---|---|---|
| XS | chest 31 to 34 in, waist 28 to 29 in | XS | XS | chest 35 to 36 in | not published |
| SM | chest 34 to 37 in, waist 29 to 31 in | XS | not published | chest 35 to 36 in | not published |
| MD | chest 37 to 41 in, waist 31 to 34 in | M | not published | chest 39 to 40 in | not published |
| LG | chest 41 to 44 in, waist 34 to 37 in | L or XL | not published | chest 41 to 42 in | not published |
| XL | chest 44 to 48 in, waist 37 to 41 in | XXL | XL | chest 46 to 48 in | not published |
| XXL | chest 48 to 52 in, waist 41 to 45.5 in | 3XL | XXL | chest 50 to 52 in | not published |
| 3XL | chest 52 to 56 in, waist 45.5 to 50 in | 4XL | 3XL | chest 53 to 55 in | not published |
| 4XL | chest 56 to 60 in, waist 50 to 54.5 in | 5XL | 4XL | chest 56 to 58 in | not published |
| 5XL | chest 60 to 64 in, waist 54.5 to 59 in | not made | 5XL | not published | 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
- lululemon size guide, read on 2026-09-18. lululemon on TrueToSize