Dog Years to Human Years Conversion


There are a number of existing calculators for converting dog years (age) to human years (age). Unfortunately, many of them use overly simplistic calculations (e.g. 1 dog years equals 7 human years). Such an approach is inaccurate since:

  • It does not take into account important factors such as dog breed (long-lived breeds have an average lifespan double that of short-lived breeds).
  • It does not take into account the fact that the ratio of adult years to total years in dogs is not the same as in people.

The following is a more accurate dog years to human years converter, along with explanations. It includes information on how to slow the aging process in dogs so that they can live a longer and healthier life. To skip the explanation and go straight to the converter, click on Dog Years to Human Years Conversion Table.


Aging Factors


Some dogs age much more slowly than others and live much longer. Therefore, one might say that one dog ages the equivalent of 10 human years each calendar year whereas for another one would day it ages the equivalent of 5 human years each calendar year. The main factors that determine how fast a dog ages and how long it normally lives are:

  • Size. On average, small dogs have a life span 1.5 times that of large dogs.
  • Breed. The breed of dog is a strong indicator of life expectancy. Small breeds tend to live longer than large breeds (as noted above). However, there are a number of exceptions. For example, it is common for a Doberman Pinscher (a large breed, weighing about 35kg or 77 pounds) to reach 15 years of age and sometimes 20, whereas the smaller Boxer is shorter-lived and often does not reach 10 years of age.
  • Gender. Female dogs tend to live longer than males (the same as in humans and many other species). Depending on breed, the female generally lives one to two years longer on average.
  • Neutering. On average, neutered dogs live longer than intact dogs. This is largely due to reduced risk of cancer, with current research showing that the sooner the neutering is done the lower the risk of cancer in later life.
  • Living conditions. Dogs which are properly feed and kept tend to live longer and be healthier than those that are not. Important factors are: diet, exercise, living conditions and medical attention. For more information, see below Lifespan versus Healthy Years.
  • Individual characteristics. Just as some people are born with a strong constitution while others are prone to illness, so are some dogs. Consequently, while one can calculate the expected lifespan of a dog based on the above factors, this is only accurate as an average and individual dogs will vary somewhat from this.

Infancy versus Maturity


Dogs spend a larger percentage of their lives in the adult phase.  This is particularly true of smaller breeds and longer lived breeds. A small dog with an expected lifespan of 15 years would be mature (sexually and physically) within 1 year. A man with an expected lifespan of 75 years (the current approximate male life expectancy in developed countries) would have the same level of maturity at 15 years of age.


This the first 1 year of the dogs life (in this example) is equal to 15 years on a man's life; in both cases it is the time required to reach maturity. The remaining 14 years of the dog's life corresponds to the remaining 60 years of the person's life, which is about 1 dog year for 4 human years.


Because dogs mature at different rates than people, it is inaccurate to say that 1 dog year is equal to so many human years (e.g. to say that 1 dog year is equal to 7 human years). One must take into account the rate of maturity, along with the aging factors discussed above, to obtain an accurate calculation.


Dog Years to Human Years


The following table matches dog years to human years. It takes into account the fact that dogs mature differently than people. It also takes into account the dog size, which is a strong factor in determining expected lifespan. However, this is just a rough indication since the other aging factors discussed above (e.g. breed) are not included in this table.


Calendar Years Under 20 lbs

(9 kg)

20-50 lbs

(9-23 kg)

50-90 lbs


Over 90 lbs

(over 41 kg)

1 15 15 14 12
2 23 24 22 20
3 28 29 29 28
4 32 34 34 35
5 36 38 40 42
6 40 42 45 49
7 44 47 50 56
8 48 51 55 64
9 52 56 61 71
10 56 60 66 78
11 60 65 72 86
12 64 69 77 93
13 68 74 82 101
14 72 78 88 108
15 76 83 93 115
16 80 87 99 123
17 84 92 104  
18 88 96 109  
19 92 101 115  
20 96 105 120  


The oldest recorded age for a dog is 27 years.


Lifespan Versus Healthy Years


The above information considers the expected lifespan and aging of dogs. In addition to considering how old one's dog will get, it is also important that a dog remain fit and healthy as long for as much of its life as possible. Although one cannot predict the health of a dog with certainty, one can increase the probability of both general health and long life through careful selection and proper care. Your vet (and perhaps your local kennel club) can advise on the following considerations:

  • Breed Health. Some breeds are generally healthy while others are known to be prone to certain diseases (e.g. hip dysplasia, brain tumours, skin allergies). If you have not yet decided on a specific breed, you may wish to discuss with your vet the various breeds you are considering and their outlook. Mixed breeds tend to be healthier (due to greater genetic diversity) than pure-breeds.
  •  Breed Lifestyle. Each of the breeds have been developed with a specific purpose in mind, be it sheep herding or family pet. The purpose for which you are using a dog and the way in which it will be kept should keep this in mind. In general, 'working dogs' need lots of space and exercise; without this they will suffer greatly mentally and to a certain extent physically. On the other hand, a 'house dog' used as a working or outside dog may suffer disease (e.g. arthritis from cold and wet) and early death if subjected to severe outside conditions.
  •  Breeder. Unscrupulous breeders (in particular 'puppy farms') will breed dogs without due consideration of their health. Serious respectable breeders will have their dogs carefully and professionally examined for inherited and other diseases before considering breeding from them. Consequently, purchasing a dog from a respected breeder (your local kennel club can provide a list), while likely more expensive initially, can save a lot of heartache and medical expenses. Due to the problem of over-breeding, in many countries it is frequently the case that the most popular breeds are the least healthy.
  •  Diet. Although dogs have different nutritional requirements then people, like us their health and lifespan will be improved through a suitable diet, with sufficient but not excessive amounts of food. A dog's requirements will depend on its age, breed and lifestyle (e.g. very active dogs need a higher proportion of carbohydrates than less active dogs). Nutritional and diet information is provided on this site.
  •  Exercise. All dogs require regular exercise (at least several times a week). The amount and type of exercise will to some extent depend on the breed and the individual dog. Working breeds (e.g. dogs breed for herding) generally require much more physical exercise, not only for their physical health but also for their mental health. It is possible to over-exercise a dog (particularly if it is very young or is elderly or if the weather is very hot) but this is rare; most dogs (like most dog owners) could use more exercise rather than less. In addition to physical exertion, exercise should also involve a certain amount of mental stimulation. Varying the route of the daily walk, playing with the dog, training it or giving it tasks to perform will all provide this.
  •  Living conditions. Dogs kept outside with inadequate shelter (from cold, wind or rain) or in poor living conditions (e.g. insufficient space, without clean water or in unsanitary conditions) will not only have a shorter lifespan, but will also be prone to early illness. That being said, what is suitable for one dog may not be suitable for another. For example, certain long-haired dogs have been breed for very cold conditions while others (such as the Newfoundland) can easily handle extremely wet and cold conditions.
  •  Medical Attention. Dogs should have vaccination against the common canine diseases. In some parts of the world the presence of certain deadly parasites (e.g. heartworm) require that dogs receive preventive medication monthly to ensure that they are not infected. Finally, like people, dogs periodically require medical treatment for illness or injury, especially as they get older.