One dog year equals seven human years: this assumption has been firmly rooted in our minds for many years. But is converting dog years into human years really that simple? We’ll show you how to calculate your dog’s age correctly.
© Mikkel Bigandt / stock.adobe.com
New research aims to help convert a dog’s age into human years.
For a long time, seven human years were equated with one dog year. However, this rule of thumb is now considered outdated, which is why new values are used for converting dog years into human years. These take into account not only the dog’s age, but also its size. The table below provides an overview of the conversion of dog years into human years:
| Dog’s Age | Human Age | Human Age | Human Age |
| Small Breeds (<15 kg) | Medium-Sized Breeds (15 to 35 kg) | Large Breeds (>45 kg) | |
| 6 months | 15 | 10 | 8 |
| 12 months/ 1 year | 20 | 18 | 14 |
| 18 months | 24 | 21 | 18 |
| 2 years | 28 | 27 | 22 |
| 3 years | 32 | 33 | 31 |
| 4 years | 36 | 39 | 40 |
| 5 years | 40 | 45 | 49 |
| 6 years | 44 | 51 | 58 |
| 7 years | 48 | 57 | 67 |
| 8 years | 52 | 63 | 76 |
| 9 years | 56 | 69 | 85 |
| 10 years | 60 | 75 | 94 |
| 11 years | 64 | 80 | 100 |
| 12 years | 68 | 85 | – |
| 13 years | 72 | 90 | – |
| 14 years | 76 | 95 | – |
| 15 years | 80 | 100 | – |
| 16 years | 84 | – | – |
| 17 years | 88 | – | – |
| 18 years | 90 | – | – |
| 19 years | 94 | – | – |
| 20 years | 100 | – | – |
According to the 7-year rule, a three-year-old dog would be 21 in human years. However, since dogs age differently from humans, this long-standing myth about converting dog years into human years ultimately turns out to be incorrect.
Scientists at the University of California San Diego revisited this question and published their findings in the journal Cell Systems in 2020.
The researchers developed a new formula to more accurately align the ageing process of dogs with that of humans. To do this, the team analysed the genetic material of 104 Labrador Retrievers spanning 16 years in age by examining what are known as DNA methylation patterns.
Since these methylation patterns regulate gene activity, they change as age increases. This allows researchers to determine the current biological age of both dogs and humans.
The results suggest that the ageing curve in dogs differs from that of humans. Young dogs age significantly faster than people do, while the ageing process slows down as they get older.
The researchers’ new formula is therefore: Human age = 16 x ln(dog age) + 31. In other words, they multiplied the natural logarithm of the dog’s age by 16 and then added 31.
This new formula for calculating dog years in human years delivers better results than the 7-year rule, but it is not yet fully developed. According to the researchers, further studies are still required.
At first glance, converting dog years into human years may seem more amusing than useful. In reality, however, this knowledge can be quite important – for example for vets. It can significantly influence the choice of diagnostic or therapeutic measures.
For this reason, it makes sense to carry out further studies on this topic in the future. However, the researchers point out that dogs of other breeds should also be included – not just Labrador Retrievers.
© Halfpoint / stock.adobe.com
How can a dog’s age be expressed in human terms? It’s not an easy question. Your dog’s biological age isn’t straightforward to determine, as it depends on various factors. In addition to the breed, the dog’s physical condition also plays a role. For instance, a dog in a normal nutritional state will, on average, live longer than a dog that is overweight.
The social environment is also believed to influence the ageing process. For example, dogs living in urban areas seem to have shorter lifespans than those that grow up in the countryside. Crossbreeds generally have an advantage over pedigree dogs when it comes to ageing.
Whether puppy, adult or senior: from dog food to dog accessories, you’ll find everything your furry friend needs in the zooplus online shop.
At the Justus-Liebig-University of Giessen I was extensively trained as a veterinarian and was able to gain experience in various fields such as small animal, large animal and exotic animal medicine as well as pharmacology, pathology and food hygiene. Since then, I have been working not only as a veterinary author, but also on my scientifically driven dissertation. My goal is to better protect animals from pathogenic bacterial organisms in the future. Besides my veterinary knowledge, I also share my own experiences as a happy dog owner and can thus understand and enlighten fears and problems as well as other important questions about animal health.
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