Size 0 fits teacup - 3lbs

Size 1 fits toy - 4-5lbs

Size 2 fits small - 6-7lbs (Yorkies) (Small Poms) (Dachshunds)

Size 3 fits 10-15(Medium Poms) (Medium Dachshunds)

Size 4 fits 15-20lbs (Shih Tzu) (Small Maltese)

Size 5 fits 25-30lbs (Maltese Poodles) (Corgis)

Size 6 fits 30-35lbs (medium doodle)

Size 7 ~40 lbs