The average chinchilla is about 10 to 15 inches (25 to 38 cm) from nose to tail tip, though individual size varies.
Breakdown
Body length: 8 to 10 inches (20 to 25 cm)
Tail length: 3 to 5 inches (7.5 to 12.5 cm)
Some chinchillas may be slightly larger or smaller than these averages.