Dog Age Calculator

Ever wondered, if your Dog was a human, How old would he/she be? Every dog breed is different, Use our Dog Age Calculator to figure out the age of your dog in Human Years. Select the dog age and the breed from this calculator and it will convert to human years.

Why convert dog years to human years?

Giving your pooch, a human age is not just a whim. Knowing their age in human years helps you determine its life stage. Once it’s life stage is determined it is easier to understand its needs and provide life-stage specific care.

In the canine world, there are six life stages:

  1. Puppy (birth to 6-7 months of age) – at this point dogs go through major physical mental changes. During this phase, it is important to focus on socialisation, training, nutrition and handling.
  2. Junior (until 1-2 years of age) – at this point dogs are sexually mature but still physically growing. This stage is usually marked by certain behavioural issues like short attention span, fear and wandering.
  3. Adult (from 1-2 years of age to middle age) – at this point dogs are socially mature and finished growing physically. However, they need proper attention regarding behaviour, physical activity, nutrition and medical needs.
  4. Mature (from middle age to three-quarters of the entire lifespan) – at this point dogs do not have specific needs but do require annual vet exams.
  5. Senior (the last quarter of the dog’s expected lifespan) – at this point dogs eat less, sleep more and are reluctant to physical activity.
  6. Geriatric (at life expectancy and beyond) – at this point dogs need bi-yearly vet examinations because their physical health can quickly decline. When parenting a geriatric dog, it is important to recognise if your dog is suffering.

Documented in the Guinness Book of World Records, the oldest hound in the world is from here in Australia, and He is a cattle dog named Bluey. He was put to sleep on 14th November 1938. He lived for 29 years and 5 months. If you converted 29 years using the below chart that would be 130 human years.

Fortunately, nowadays, they live much longer lives than their canine ancestors. In 1900 less than 20% of the dogs lived past the age of 6. In 2010, that percentage was 44%.

How old is this Springer Spaniel

How to calculate Dog years to Human years

During Dog’s first two years they age faster than humans, so need to multiply by 15, and after this period ratio gradually slow down to 1:5, by using the calculator you would be able to convert your dog’s age to human years.

People have been comparing human to dog’s life span for centuries. The origins of those comparisons are obscure and scarce. However, evidence shows that people were trying to calculate their dogs’ ages since the 1200s. An inscription on the Cosmati Pavement in Westminster Abbey, dating back to 1268, states that one human year is equivalent to nine years. Later on, in the 1950s, dogs had two years trimmed off their lifespan and the 7-year rule became popular. This 7:1 ratio was based on pure logic and statistics. At that time, on average, humans lived to about 70 years while their four-legged mates lived to about 10 years. In 1953, based on the research conducted by A. Lebeau, it was established that:

  • During their first year of life, dogs age 15-20 times faster than humans
  • Then the ration gradually slows down to 1:5.

To be more accurate:

  • A 1-year-old puppy equals a 10-15 years old human. Both are sexually mature and physically grown but still a bit lanky.
  • A dog’s second year of life equals 3-8 human years. This is in terms of mental and physical maturity.
  • After the first two years of life, the ratio is 5:1 for small and medium breeds; 6:1 for large breeds and 7:1 for giant breeds. To illustrate this, a 10-year-old Great Dane would be 70 dog years old, a 10-year-old Cocker Spaniel would be 60 years old and a 10-year-old Pug would be only 50 human years old.

Dog Years Chart

Dog age chart

Why do smaller dogs live longer than larger dogs?

Generally speaking, large mammals like elephants and rhinos, live longer than small mammals, like mice and guinea pigs. However, when speaking about dogs, this is not true. It is well-established that smaller dogs live longer than large dogs. For many years, this peculiar phenomenon has baffled scientists. The relationship between body mass and life expectancy is quite complex and not fully understood. Nevertheless, recent studies suggest that a dog’s life expectancy is reduced by 1 month for every 2 kilograms of body mass. The reason why is not known but there are several evidence-based and objective options:

  • Larger dogs tend to succumb to age-related illnesses sooner than smaller dogs
  • Due to their accelerated growth, larger dogs are at higher risk of abnormal cell growth and consequently cancerous changes.

Great Danes grow quickly in size but do not reach maturity until 2 years old. Their average lifespan is 6-8 years. On the flip side, Yorkshire Terriers reach maturity when less than 12 months old and have a particularly long lifespan that often exceeds 15 years. Therefore, both the lifespan and the ageing rate depend on the breed.

A 4-year old Miniature Schnauzer is younger than a 4-year-old Neapolitan Mastiff. However, since smaller breeds mature more quickly, it is only logical to assume that a 1-year-old Chihuahua is more mature than a 1-year-old Great Dane.

Dogs are considered old when they reach three-quarters of their life expectancy. In general, dogs enter their senior years when 7 years old. More precisely:

  • Large dog breeds are considered seniors after the age of 6
  • Medium dog breeds and mutts are considered seniors after the age of 7
  • Small dog breeds are considered seniors after the age of 9.

It should be noted that a dog’s life expectancy is not determined exclusively by its breed, weight and size. This variable is affected by the following factors as well:

  • Lifestyle
  • Nutrition
  • Type and extent of physical activity
  • Genetic factors
  • Physiological state (neutered, spayed or intact)
  • Place of residence (indoors, outdoors, wild).
Dog weight vs age chart

The smaller version of the above calculator

Below table would show, how dogs ageing with human years generally, please use the above calculator to calculate according to your breed as it will be more accurate.

Dog Years Human Years
6 months 10 years
1 year 31 years
2 years 42.1 years
3 Years 48.6
4 53.2
5 56.8
6 59.7
7 62.1
8 64.3
9 66.2
10 67.8
11 69.4
12 70.8
13 72
14 73.2
15 74.3
16 75.4
17 76.3
18 77.2
19 78.1
20 78.9
21 79.7
22 80.5
23 81.2
24 81.8
25 82.5
26 83.1
27 83.7
28 84.3
29 84.9
30 85.4


In a nutshell, the first year of a dog’s life equals 15 human years. After that, the dog’s ageing pace is determined by its size and breed. This is mainly due to selective breeding. Dogs come in a huge variety of breeds and sizes. Therefore, their ageing paces and life spans significantly differ within the specie.

So…all in all, the seven-year myth is not true and it has not been true for a relatively long time now, however, even today most dog owners default to this traditional rule, use our Dog age calculator to get the correct results. As the curator of the Charles R. Connor Museum at the Washington State University, Kelly M. Cassidy, who studied longevity in dogs said:, You can’t really kill the seven-year rule’’. And maybe it should not be killed. From a health standpoint, the rule can be used to illustrate how fast dog ages compared to a human. Therefore, the rule although not accurate, is quite convenient.