Decathlon to Old Navy leggings size

The short answer

Decathlon 2XS is Old Navy XXS by the two brands' own charts. 2 of 7 Decathlon sizes land on a different label at Old Navy.

Both brands publish the body waist each size is cut for, so every row matches a waist, not a tag.

Every Decathlon size read across to Old Navy. Letter sizes on the left, Letter on the right.
Decathlon	Decathlon builds it for	Old Navy, by chart	Same label	Old Navy builds it for	Old Navy also prints
2XS	waist 23.6 to 24.8 in, hip 31.1 to 33.5 in	XXS	XXS	waist 24 in, hip 34.5 in	US numeric 00
XS	waist 25.2 to 26.8 in, hip 33.5 to 35.4 in	XS	XS	waist 25 to 26 in, hip 35.5 to 36.5 in	US numeric 0-2
S	waist 27.2 to 28.7 in, hip 35.4 to 37.8 in	S	S	waist 27 to 28 in, hip 37.5 to 38.5 in	US numeric 4-6
M	waist 29.1 to 31.1 in, hip 37.8 to 40.2 in	M	M	waist 29 to 30 in, hip 39.5 to 40.5 in	US numeric 8-10
L	waist 31.5 to 33.9 in, hip 40.2 to 42.5 in	L	L	waist 31.5 to 33.5 in, hip 42 to 44 in	US numeric 12-14
XL	waist 34.3 to 36.6 in, hip 42.5 to 44.9 in	XL or L	XL	waist 36.3 to 39 in, hip 46.5 to 49 in	US numeric 16-18
2XL	waist 37 to 39.4 in, hip 44.9 to 47.2 in	XL	XXL	waist 36.3 to 39 in, hip 46.5 to 49 in	US numeric 16-18

Tinted rows change label or sit between two sizes. Read from the two charts only; no formula and no averaging.

What wearers say

Charts describe a garment. People who own both brands describe a fit, and their answer ranks above this table once five of them stand behind it. Pick your size in the converter to see whether there are enough yet.

Open in the converter Add an item you own

Sources

Decathlon size guide, read on 2026-09-18.
Old Navy size guide, read on 2026-09-17. Old Navy on TrueToSize

Old Navy to Decathlon