This dress features a stretch fabric, lace details, & adjustable spaghetti straps. Strechy! It actually has an adjustable strap for the chest area. So if you have big boobs you can loosen it or if you have small boobs you can make it tighter. S; 13 inches from armpit to armpit. 31.5 inches long M; 14 inches from armpit to armpit. 32.5 inches long