The life expectancy of any dog is commonly expressed in terms of dog years by us and it depends entirely on the dog’s breed, size as well as the dog’s surroundings. Various other factors affect the life expectancy of a dog. A dog’s life span changes according to the diet provided to him and also by the number of medical problems the dog tends to face over the years. The average life span of the small dog like Chihuahua is about 15 to 16 years, while medium sized the dogs like Border Collies have a life span of 10 to 13 years. It can be noticed big dogs like Great Dean live up to only 7 to 8 years. The calculation of the life expectancy of particular dog can be accurately done with the help of “size or the specific breed calculator”, which is said to be one of the most accurate age measurement schemes available. The size or specific bree we buy any house d calculator gives approximate results about the dog’s predictable lifespan based on the size as well as the breed of the dog. It is generally assumed that, on an average, “one human year equals to seven dog years”. This statement may not be appropriate, since the first two years are jointly represented by 18-25 years in such schemes and because the entire ratio cannot be generalized for all the dogs though, they belong to different sizes and breeds. An exact ratio of dog years vs. human year cannot be formulated. However, some obvious features remain similar between both aging humans and dogs. It is generally assumed that the human equivalent of a one-year dog is supposedly fully grown by both mental and physical aspects. Dogs like humans tend to develop advance muscular features as they grow along with a similar mental development.