This is a beautiful and comforting shirt in like new condition! I truly don’t know if it is a S or M as I cannot find any size on the actual garmet. It is 21.5 inches armpit to armpit and 23.5 inches long measuring from the back top of collar. Soft, comfortable and casually chic, this quality piece is waiting to join your forever wardrobe. Please see photos for more information on the style, fit and fabric content. Check out my website, LCM Lifestyle and sign up to receive my exclusive subscriber emails! Link in bio. Why Not Live Beautifully Each Day?