Lululemon to Under Armour size
The short answer
lululemon XS is Under Armour SM by the two brands' own charts. 9 of 9 lululemon 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.
| lululemon | lululemon builds it for | Under Armour, by chart | Same label | Under Armour builds it for | Under Armour also prints |
|---|---|---|---|---|---|
| XS | chest 35 to 36 in | SM | XS | chest 34 to 37 in, waist 29 to 31 in | not published |
| S | chest 37 to 38 in | MD | not published | chest 37 to 41 in, waist 31 to 34 in | not published |
| M | chest 39 to 40 in | MD | not published | chest 37 to 41 in, waist 31 to 34 in | not published |
| L | chest 41 to 42 in | LG | not published | chest 41 to 44 in, waist 34 to 37 in | not published |
| XL | chest 43 to 45 in | LG | XL | chest 41 to 44 in, waist 34 to 37 in | not published |
| XXL | chest 46 to 48 in | XL | XXL | chest 44 to 48 in, waist 37 to 41 in | not published |
| 3XL | chest 50 to 52 in | XXL | 3XL | chest 48 to 52 in, waist 41 to 45.5 in | not published |
| 4XL | chest 53 to 55 in | 3XL | 4XL | chest 52 to 56 in, waist 45.5 to 50 in | not published |
| 5XL | chest 56 to 58 in | 4XL | 5XL | chest 56 to 60 in, waist 50 to 54.5 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
- lululemon size guide, read on 2026-09-18. lululemon on TrueToSize
- Under Armour size guide, read on 2026-09-18. Under Armour on TrueToSize