Marks & Spencer to Old Navy size
The short answer
Marks & Spencer S is Old Navy XS by the two brands' own charts. 7 of 7 Marks & Spencer sizes land on a different label at Old Navy.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
On 1 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 | Old Navy, by chart | Same label | Old Navy builds it for | Old Navy also prints |
|---|---|---|---|---|---|
| XS | chest 32 to 34 in | not made | XS | not published | not published |
| S | chest 35 to 37 in | XS | S | chest 36 to 37 in, neck 13 to 13.5 in, sleeve 31.5 to 32 in | not published |
| M | chest 38 to 40 in | S | M | chest 38 to 39 in, neck 14 to 14.5 in, sleeve 32.5 to 33 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 to 34 in | not published |
| XL | chest 44 to 46 in | L | XL | chest 44 to 46 in, neck 16 to 16.5 in, sleeve 34.5 to 35 in | not published |
| XXL | chest 47 to 49 in | XL | XXL | chest 48 to 50 in, neck 17 to 17.5 in, sleeve 35.5 to 36 in | not published |
| XXXL | chest 50 to 52 in | XXL | XXXL | chest 51 to 53 in, neck 18 to 18.5 in, sleeve 36.5 to 37 in | not published |
| 4XL | chest 52 to 54 in | XXL | XXXXL | chest 51 to 53 in, neck 18 to 18.5 in, sleeve 36.5 to 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.
- Old Navy size guide, read on 2026-09-18. Old Navy on TrueToSize