How big is a full-grown grey Mastiff?

A fully grown Mastiff stands between 27 inches and 32 inches high at the shoulder and weighs between 130 and 220 pounds. They are considered the largest dog breed in the world. Color has no bearing on their size.

Males are typically taller and heavier than females. Males are 30 inches tall at maturity and may weigh up to 250 pounds. Although females are smaller, they still reach weights of up to 200 pounds. The largest dog ever recorded, as of 1989, was a male Mastiff that weighed 343 pounds, stood 35 inches at the shoulder and was 8.25 feet long from snout to tail.