Why your dog isn't the age you think

It also changes a lot depending on the size and age of the dog, a chihuahua will be physically grown at 6 months old and considered an adult at 6 years,  and they can live up to 16-17 years

But a great dane takes 18 months to be physically grown and is considered an adult at 2.5-3 years,  then they live approx 8-10 years, so they mature slower but age faster