Reference size:

XS: Back length 20CM, chest 30CM
S: Back length 25CM, chest 35CM
M: Back length 30CM, chest 40CM
L: Back length 35CM, chest 45CM
XL: Back length 40CM, chest 50CM

XS (recommended weight 0.5-1kg)
S (recommended weight 1.5-2kg)
M (recommended weight 2.5-3.5kg)
L (recommended weight 4-4.5kg)
XL (recommended weight 5-6.5kg)

Note:
1. Manual measurements may have 2-3 cm error.
2. For two-legged Clothes, please pay attention to chest girth, and for four legged, must fit for chest girth and back length.
3. For the growing pet, you'd better choose the bigger size.
Please, make sure of the actual measurements will fit you!