9 in dog years roughly equals 56 in human years.
This calculation was made for a medium-sized dog (21 to 50 pounds) using the recommendations from the AKC (American Kennel Club).
There are 2 ways of calculating the conversion from human years to dog years. The above result was calculated using the more correct way, we’ll explain what makes the other way incorrect later in this article.
The table below shows dog years and their equivalent to human years, with different columns for different sizes.
| Dog's Age in Years | Human Years (Small Dog) | Human Years (Medium Dog) | Human Years (Large Dog) |
|---|---|---|---|
| 1 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 |
| 3 | 28 | 28 | 28 |
| 4 | 32 | 32 | 32 |
| 5 | 36 | 36 | 36 |
| 6 | 40 | 42 | 45 |
| 7 | 44 | 47 | 50 |
| 8 | 48 | 51 | 55 |
| 9 | 52 | 56 | 61 |
| 10 | 56 | 60 | 66 |
| 11 | 60 | 65 | 72 |
| 12 | 64 | 69 | 77 |
| 13 | 68 | 74 | 82 |
| 14 | 72 | 78 | 88 |
| 15 | 76 | 83 | 93 |
| 16 | 80 | 87 | 99 |
Calculating how many human years is 9 in dog years
As mentioned above, there are 2 main ways of calculating dog years to human years and vice versa. There’s a correct way and an incorrect way.
The incorrect calculation
The majority of people still believe that one dog year equals 7 dog years. This assumption was probably first introduced in the 1950s, however this isn’t the best method of calculating it.
There has been a lot of research since then that disproves this ratio of 7 to 1, people continue to believe it. The formula could have been based on the assumption that dogs live to about 10 years old and humans up can live to 70, however we don’t know the date it was first introduced.
So while the 7 to 1 rule is simple to remember and calculate however, it’s sadly incorrect.
The correct formula
The correct way of converting human years into dog years is a bit more complex.
The American Veterinary Medical Association has the following to be said about it:
- The beginning year of a medium-sized dog’s lifespan equals around 15 human years.
- The second year in a dog’s lifespan equals about 9 human years.
- From that point forward each human year is equal to the equivalent of four to five dog years.
Keep in mind that smaller dogs tend to live longer than bigger dogs. Scientists concluded that every 4.4 pounds of body mass reduced a dog’s life expectancy by about a month.
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