GU to Marks & Spencer size
The short answer
GU S is Marks & Spencer XS by the two brands' own charts. 6 of 7 GU sizes land on a different label at Marks & Spencer.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
| GU Japan sizing | GU builds it for | Marks & Spencer, by chart | Same label | Marks & Spencer builds it for | Marks & Spencer also prints |
|---|---|---|---|---|---|
| XS | chest 29.9 to 33.1 in, waist 25.2 to 28.4 in | XS | XS | chest 32 to 34 in | not published |
| S | chest 31.5 to 34.7 in, waist 26.8 to 29.9 in | XS | S | chest 32 to 34 in | not published |
| M | chest 34.7 to 37.8 in, waist 29.9 to 33.1 in | S | M | chest 35 to 37 in | not published |
| L | chest 37.8 to 40.9 in, waist 33.1 to 36.2 in | M | L | chest 38 to 40 in | not published |
| XL | chest 40.9 to 44.1 in, waist 36.2 to 39.4 in | L | XL | chest 41 to 43 in | not published |
| XXL | chest 44.1 to 47.2 in, waist 39.4 to 42.5 in | XL | XXL | chest 44 to 46 in | not published |
| 3XL | chest 47.2 to 50.4 in, waist 42.5 to 45.7 in | XXL | XXXL | chest 47 to 49 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
- GU Japan sizing size guide, read on 2026-09-25.
- Marks & Spencer size guide, read on 2026-09-18.