This is a new leotard but without tags. Inside there is a tag that shows AM but not sure if that’s the size. Photos with a tape measure in various positions is probably the best way to size since gymnasts bodies vary and age is probably not the best way to determine size. Measurements: Across chest from bottom of arm opening: approximately 14-1/2” From top of neck to bottom seam: approximately 21” From bottom of arm opening to top of leg opening along the side seam: approximately 10”