Gap Jean Jacket Blazer Style

This is such a cute jacket. The tag says size XL (12). I have worn it and it fits like a women's size small or a teen or preteen XL. The measurements are as follows and are approximate and done with a dressmakers measuring tape. Length- 21 inches shoulder to bottom of hem Bust- 16 inches under arm seam to underarm seam across the front and buttoned. Waist- 15.5 inches across the waist seam. Arm- 21 shoulder to cuff. Any questions please ask.