Marks & Spencer to American Eagle size
The short answer
Marks & Spencer S is American Eagle XS by the two brands' own charts. 7 of 8 Marks & Spencer sizes land on a different label at American Eagle.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
On 3 sizes the charts land two or more sizes from the same label. Brands do not measure the body the same way, so on those rows treat the chart answer and the same label as the two ends of a range.
| Marks & Spencer | Marks & Spencer builds it for | American Eagle, by chart | Same label | American Eagle builds it for | American Eagle also prints |
|---|---|---|---|---|---|
| XS | chest 32 to 34 in | XS | XS | chest 35 to 36 in, neck 13.5 to 14 in, sleeve 31.5 in | not published |
| S | chest 35 to 37 in | XS | S | chest 35 to 36 in, neck 13.5 to 14 in, sleeve 31.5 in | not published |
| M | chest 38 to 40 in | S | M | chest 37 to 39 in, neck 14.5 to 15 in, sleeve 32.5 in | not published |
| L | chest 41 to 43 in | M | L | chest 40 to 42 in, neck 15 to 15.5 in, sleeve 33.5 in | not published |
| XL | chest 44 to 46 in | L | XL | chest 43 to 45 in, neck 15.5 to 16 in, sleeve 34.5 in | not published |
| XXL | chest 47 to 49 in | XL | XXL | chest 46 to 48 in, neck 16.5 to 17 in, sleeve 35.5 in | not published |
| XXXL | chest 50 to 52 in | XXL | XXXL | chest 49 to 51 in, neck 17 to 18 in, sleeve 36.5 in | not published |
| 4XL | chest 52 to 54 in | XXXL | not published | chest 52 to 54 in, neck 18 to 19 in, sleeve 37 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.
- American Eagle size guide, read on 2026-09-18. American Eagle on TrueToSize