Marks & Spencer to Under Armour size
The short answer
Marks & Spencer S is Under Armour SM by the two brands' own charts. 6 of 8 Marks & Spencer 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.
| Marks & Spencer | Marks & Spencer builds it for | Under Armour, by chart | Same label | Under Armour builds it for | Under Armour also prints |
|---|---|---|---|---|---|
| XS | chest 32 to 34 in | XS | XS | chest 31 to 34 in, waist 28 to 29 in | not published |
| S | chest 35 to 37 in | SM | not published | chest 34 to 37 in, waist 29 to 31 in | not published |
| M | chest 38 to 40 in | MD | not published | chest 37 to 41 in, waist 31 to 34 in | not published |
| L | chest 41 to 43 in | LG | not published | chest 41 to 44 in, waist 34 to 37 in | not published |
| XL | chest 44 to 46 in | XL | XL | chest 44 to 48 in, waist 37 to 41 in | not published |
| XXL | chest 47 to 49 in | XL | XXL | chest 44 to 48 in, waist 37 to 41 in | not published |
| XXXL | chest 50 to 52 in | XXL | 3XL | chest 48 to 52 in, waist 41 to 45.5 in | not published |
| 4XL | chest 52 to 54 in | 3XL | 4XL | chest 52 to 56 in, waist 45.5 to 50 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
- Marks & Spencer size guide, read on 2026-09-18.
- Under Armour size guide, read on 2026-09-18. Under Armour on TrueToSize