English Mastiff males average around 160 pounds full grown while females typically weigh around 150 pounds as adults. The English Mastiff breed is one of the heaviest, and males can grow to exceed 200 pounds.
An adult male English Mastiff grows to an average length of 30 inches and an adult female averages 27 inches in length. They do not need a lot of room to run around inside, as they tend to remain fairly inactive indoors. Since they are prone to bloat, this breed should be fed two small meals a day rather than one big one. Although known as gentle giants, most English Mastiffs instinctively protect their families.