Marks & Spencer to Gap size
The short answer
Marks & Spencer S is Gap XS by the two brands' own charts. 4 of 8 Marks & Spencer sizes land on a different label at Gap.
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 | Gap, by chart | Same label | Gap builds it for | Gap also prints |
|---|---|---|---|---|---|
| XS | chest 32 to 34 in | XS | XS | chest 35 to 36 in, neck 13.5 to 14 in, sleeve 31 to 32 in | not published |
| S | chest 35 to 37 in | XS | S | chest 35 to 36 in, neck 13.5 to 14 in, sleeve 31 to 32 in | not published |
| M | chest 38 to 40 in | M | M | chest 39 to 41 in, neck 15 to 15.5 in, sleeve 33 to 34 in | not published |
| L | chest 41 to 43 in | L | L | chest 42 to 44 in, neck 16 to 16.5 in, sleeve 34 to 35 in | not published |
| XL | chest 44 to 46 in | XL | XL | chest 45 to 48 in, neck 17 to 17.5 in, sleeve 35 to 35.5 in | not published |
| XXL | chest 47 to 49 in | XL | XXL | chest 45 to 48 in, neck 17 to 17.5 in, sleeve 35 to 35.5 in | not published |
| XXXL | chest 50 to 52 in | XXL | XXXL | chest 49 to 52 in, neck 18 to 18.5 in, sleeve 35.5 to 36 in | not published |
| 4XL | chest 52 to 54 in | XXL or XXXL | not published | chest 49 to 52 in, neck 18 to 18.5 in, sleeve 35.5 to 36 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.
- Gap size guide, read on 2026-09-18. Gap on TrueToSize