Measurements are in inches and were taken from the garment laid flat unless otherwise stated.

Size Shoulder Chest Hem Sleeve Back length
XS 36 19 19.5 17.5 21 26
S 38 20 20 18 22 27
M 40 21 20 18.5 23 28
L 42 22 21 19 23.5 29

These jumpers are quite stretchy. The source recommends ordering the size corresponding to the wearer's measured chest for a fitted look.