Most average size cats wear medium. If your cat is very small boned, choose the small size. Very large boned cats tend towards large. Kittens usually are big enough to wear Soft Claws by 12-16 weeks of age.

GUIDELINES

Kitten
Soft Claws will fit most kittens by the time they reach the age of 12-16 weeks. To test, try a nail cap on first without the adhesive. If it looks too big, don’t glue it on. The nail cap should fit snugly, like a glove. The nail caps can also be trimmed to fit if needed.

Kittens up to about 5 months of age and 5 pounds body weight generally fit into the kitten size.

It is best not to trim kitten's nails before application because their nails are so small.

Small
Approximately 6 months of age.
Approximately 6-8 pounds.

Some kittens at 5 months may need the small size if they are growing fast or are large-breed cats.

Small-boned adult cats often wear the small size. If your cat seems smaller than an average full-grown cat, choose small.

Medium
Approximately 9-13 pounds. Most adult average size cats wear medium.

Large
Approximately 14 pounds and up. Very large-boned and large-breed cats wear large. Maine Coons, for example, are very large cats and generally wear large.