Using a tape measure (or a piece of string that you measure on a flat ruler later), take the measurements below while your cat is standing up. Remember to draw the tape measure tight enough to compress any fur underneath!
Small - Chest: 25-29cm, Neck:20-25cm
Medium - Chest: 31-37cm, Neck:23-29cm
Large - Chest: 33-39cm, Neck:28-32cm
XL - Chest: 38-44cm, Neck:30-35cm
XXL - Chest: 40-46cm, Neck:34-38cm
XXXL - Chest: 46-59cm, Neck:36-42cm