Size S (Approx ages 0-1 yrs): approx 13.5" long & 19-20" chest diameter.
Size M (Approx ages 2-3 yrs): approx 14.5" long & 20-21" chest diameter.
Size L (Approx ages 3-4 yrs): approx 15.5" long & 21-22" chest diameter.
Size XL (Approx ages 5-6 yrs): approx 16.5" long & 22-23" chest diameter.
If you have any further questions about sizing, please e-mail us at info@shoplittlelady.com