GU to Gap clothing size

The short answer

GU XL is Gap 8 or 10 by the two brands' own charts.

Both brands publish the body bust each size is cut for, so every row matches a bust, not a letter or a number.

Every GU Japan sizing size read across to Gap. Letter sizes on the left, US on the right.
GU Japan sizing	GU builds it for	Gap, by chart	Same label	Gap builds it for	Gap also prints
XS	bust 27.6 to 29.5 in, waist 21.3 to 23.2 in, hip 30.3 to 31.9 in	not made	not published	not published	not published
S	bust 29.5 to 31.5 in, waist 23.2 to 24.8 in, hip 31.9 to 33.5 in	000	not published	bust 30.3 in, waist 24 in, hip 33.3 in	Letter XXS
M	bust 31.5 to 33.5 in, waist 24.8 to 26.4 in, hip 33.5 to 35 in	0	not published	bust 32.3 in, waist 25.5 in, hip 35.3 in	Letter XS
L	bust 33.5 to 35.4 in, waist 26.4 to 28 in, hip 35 to 36.6 in	4	not published	bust 34.3 in, waist 27.5 in, hip 37.3 in	Letter S
XL	bust 35.4 to 37.8 in, waist 28 to 30.3 in, hip 36.6 to 38.6 in	8 or 10	not published	bust 36.3 in, waist 29.5 in, hip 39.3 in	Letter M
XXL	bust 37.8 to 40.2 in, waist 30.3 to 32.7 in, hip 38.6 to 40.6 in	12	not published	bust 38.8 in, waist 32 in, hip 41.8 in	Letter L
3XL	bust 40.2 to 43.3 in, waist 32.7 to 35.4 in, hip 40.6 to 43.3 in	16	not published	bust 42 in, waist 35.5 in, hip 45.3 in	Letter XL

Tinted rows change label or sit between two sizes. 1 sizes have no counterpart on the Gap chart. Read from the two charts only; no formula and no averaging.

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.

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Sources

GU Japan sizing size guide, read on 2026-09-25.
Gap size guide, read on 2026-09-18. Gap on TrueToSize

Gap to GU