Men's Large shirt (dress shirt): 16–16.5" neck, 34–35" sleeve, 42–44" chest. Casual Large: 42–44" chest.
Women's Large shirt: US size 12–14, 40–42" bust, 32–34" waist.
Brands vary by 2–3 inches in either direction. Athletic-fit shirts run smaller through the chest; relaxed-fit run larger.
If you're between, choose based on shoulder fit. The shoulder seam should sit at the bony point of your shoulder.
European Large: men's EU 52, women's EU 42–44.