Does this seem accurate? The Wings + Horns Navy Henley is listed here at Haven with a 1/2-chest (pit-to-pit?) measurement of 44 cm. (17.3") for a medium and 48 cm. (18.9") for a large. At those measurements, I think even a large would be too tight on me, as I typically take something around 19.5" P2P in non-layered shirts.