One human year is not exactly seven dog years.
The seven-to-one ratio used to measure dog years was just an average figured by comparing human life expectancy with dog life expectancy.
Here’s how it more accurately breaks down.
The first year of a dog’s life is equal to about nineteen or twenty human years, give or take a few years.
In that first year, the dog will go through infancy, young childhood, puberty, and the rebellious teen years.
By the time it hits its second year, your dog is a young adult.
From that point on, you can fairly figure that a human year equals about four dog years.
In other words, your three-year-old dog is not exactly twenty-one in dog years.
His Tale Cut Short and His Years Cut Long.