15 Amazing Facts About Boston Terriers You Probably Never Knew By Allen Abby - The average lifespan of the Boston Terriers is between 11 to 15 years. In reality, it all depends on the care and the living conditions of the dog. Boston terriers are not large dogs in nature. Their average height is between 15-17 inches (38-43 cm). Their weight average is somewhere between 7.7 — 24 Lbs (4,5-11 kg). Please follow and like us: