Old Navy to MUJI size
The short answer
Old Navy XS is MUJI M by the two brands' own charts. 5 of 5 Old Navy sizes land on a different label at MUJI.
Both brands publish the body chest each size is cut for, so every row matches a chest, not a letter.
On 4 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.
| Old Navy | Old Navy builds it for | MUJI Japan sizing, by chart | Same label | MUJI builds it for | MUJI also prints |
|---|---|---|---|---|---|
| XS | chest 36 to 37 in, neck 13 to 13.5 in, sleeve 31.5 to 32 in | M | XS | chest 34.7 to 37.8 in, waist 29.9 to 33.1 in, hip 35.4 to 38.6 in | not published |
| S | chest 38 to 39 in, neck 14 to 14.5 in, sleeve 32.5 to 33 in | L | S | chest 37.8 to 40.9 in, waist 33.1 to 36.2 in, hip 38.6 to 41.7 in | not published |
| M | chest 40 to 42 in, neck 15 to 15.5 in, sleeve 33.5 to 34 in | XL | M | chest 40.9 to 44.1 in, waist 36.2 to 39.4 in, hip 41.7 to 44.9 in | not published |
| L | chest 44 to 46 in, neck 16 to 16.5 in, sleeve 34.5 to 35 in | XXL | L | chest 44.1 to 47.2 in, waist 39.4 to 42.5 in, hip 44.9 to 48 in | not published |
| XL | chest 48 to 50 in, neck 17 to 17.5 in, sleeve 35.5 to 36 in | XXL | XL | chest 44.1 to 47.2 in, waist 39.4 to 42.5 in, hip 44.9 to 48 in | not published |
| XXL | chest 51 to 53 in, neck 18 to 18.5 in, sleeve 36.5 to 37 in | not made | XXL | not published | not published |
| XXXL | chest 55 to 57 in, neck 19 to 19.5 in, sleeve 37.5 to 38 in | not made | not published | not published | not published |
| XXXXL | chest 58 to 60 in, neck 20.5 to 21 in, sleeve 38.5 to 39 in | not made | not published | not published | 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
- Old Navy size guide, read on 2026-09-18. Old Navy on TrueToSize
- MUJI Japan sizing size guide, read on 2026-09-25.