Gap to Marks & Spencer size
The short answer
Gap XS is Marks & Spencer S by the two brands' own charts. 3 of 7 Gap 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.
| Gap | Gap builds it for | Marks & Spencer, by chart | Same label | Marks & Spencer builds it for | Marks & Spencer also prints |
|---|---|---|---|---|---|
| XS | chest 35 to 36 in, neck 13.5 to 14 in, sleeve 31 to 32 in | S | XS | chest 35 to 37 in | not published |
| S | chest 37 to 38 in, neck 14 to 14.5 in, sleeve 32 to 33 in | S or M | S | chest 35 to 37 in | not published |
| M | chest 39 to 41 in, neck 15 to 15.5 in, sleeve 33 to 34 in | M | M | chest 38 to 40 in | not published |
| L | chest 42 to 44 in, neck 16 to 16.5 in, sleeve 34 to 35 in | L | L | chest 41 to 43 in | not published |
| XL | chest 45 to 48 in, neck 17 to 17.5 in, sleeve 35 to 35.5 in | XL or XXL | XL | chest 44 to 46 in | not published |
| XXL | chest 49 to 52 in, neck 18 to 18.5 in, sleeve 35.5 to 36 in | XXXL | XXL | chest 50 to 52 in | not published |
| XXXL | chest 55 in, neck 18.8 in, sleeve 36.5 in | 4XL | XXXL | chest 52 to 54 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
- Gap size guide, read on 2026-09-18. Gap on TrueToSize
- Marks & Spencer size guide, read on 2026-09-18.