MENS: These t-shirts are generously sized.
Small 36-38" chest (20" flat measurement armpit to armpit)
Med 38 - 40" chest (21" flat measurement armpit to armpit)
Large 40 - 42" chest (22" flat measurement armpit to armpit)
XLarge 42 - 44" chest (23" flat measurement armpit to armpit)
WOMENS'
Small UK 8/10 (Actual measurements - Armpit to armpit 42cm, neck to bottom of T-shirt 59cm)
Med UK 10/12 (Actual measurements - Armpit to armpit 45cm, neck to bottom of T-shirt 61cm)
Lge UK 12/14 (Actual measurements - Armpit to armpit 46cm, neck to bottom of T-shirt 65cm)
X/Lge UK 14/16 (Actual measurements - Armpit to armpit 50cm, neck to bottom of T-shirt 66cm)