Dog Age Calculator
Convert your dog’s age into human years using size-adjusted veterinary data, and see what life stage that puts it in.
Leave at 0 if you only know the year.
Typical lifespan 11-14 years. Senior from about 10 years.
Human age equivalent
24.0 human years
Adolescent. Physically near-grown but behaviourally immature. Training regressions are normal.
- Life stage
- Adolescent
- Becomes senior at
- 10 years (in 8.0)
- Epigenetic clock estimate
- 42.1 years
- What “multiply by 7” would say
- 14.0 years
The multiply-by-seven figure is shown only for contrast. It is wrong at every age, and most wrong in the first two years, when a dog does most of its ageing.
How this is calculated
There are two credible ways to answer this question, and this page shows both. The headline figure comes from size-tiered life-stage data. The second figure comes from the epigenetic clock. Neither is the multiply-by-seven rule, which has no evidence behind it.
1. The size-tiered table
Dogs do most of their ageing early. The first year is worth about 15 human years and the second about 9, after which the pace settles and diverges by size: roughly 4 human years per dog year for a small breed, and 7 or more for a giant one.
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 12 |
| 2 years | 24 | 24 | 24 | 22 |
| 3 years | 28 | 28 | 28 | 31 |
| 4 years | 32 | 32 | 32 | 38 |
| 5 years | 36 | 36 | 36 | 45 |
| 6 years | 40 | 42 | 45 | 49 |
| 7 years | 44 | 47 | 50 | 56 |
| 8 years | 48 | 51 | 55 | 64 |
| 9 years | 52 | 56 | 61 | 71 |
| 10 years | 56 | 60 | 66 | 79 |
| 11 years | 60 | 65 | 72 | 86 |
| 12 years | 64 | 69 | 77 | 93 |
| 13 years | 68 | 74 | 82 | 100 |
| 14 years | 72 | 78 | 88 | 107 |
| 15 years | 76 | 83 | 93 | 114 |
| 16 years | 80 | 87 | 99 | 121 |
Ages between whole years are interpolated. Below one year the value is scaled linearly from birth, which is an approximation: puppy development is not actually linear, but no published table gives month-by-month figures, and stating the approximation is better than inventing precision.
2. The epigenetic clock
human age = 16 × ln(dog age) + 31 Wang and colleagues (2020) compared methylation patterns at conserved genomic sites in dogs and humans and fitted this curve. It captures the front-loaded shape of dog ageing well, but it was built on Labrador Retrievers, so it applies one curve to every breed and size. It is undefined below one year, where the logarithm turns negative.
Why not multiply by seven?
The seven-times rule fails in both directions at once. It says a one-year-old dog is seven, an age at which a human cannot reproduce and is nowhere near skeletally mature, while a dog can do both. Then at the other end it says a 12-year-old Great Dane is 84 when the physiological equivalent is closer to 100. It also ignores size completely, which is the single biggest factor after age itself.
Sources
- American Animal Hospital Association, Canine Life Stage Guidelines.
- American Kennel Club, dog age by size charts.
- Wang T. et al., “Quantitative Translation of Dog-to-Human Aging by Conserved Rate of Epigenetic Drift”, Cell Systems, 2020.
What changes at each life stage
The number is interesting; the life stage is what actually changes your dog's care. Puppies need vaccination courses, socialisation windows and growth-appropriate food. Adolescents look grown but regress in training, and this is the age at which most dogs are surrendered to shelters.
Adult dogs need an annual exam and steady body condition. Mature dogs benefit from watching weight and dental health, since both quietly worsen. Senior dogs do better on twice-yearly exams with screening bloodwork, because the conditions that shorten their lives are far more treatable when caught early.
Common questions
Is one dog year really seven human years?
No. The rule appears to have started as a rough way of saying dogs live about a seventh as long as people, and it was never based on data. It is most wrong early: a one-year-old dog is closer to a 15-year-old human than a 7-year-old, because dogs reach sexual and skeletal maturity within the first year.
Why does size change the answer?
Large and giant breeds age faster after maturity. A 7-year-old Great Dane is roughly equivalent to a 56-year-old human, while a 7-year-old Chihuahua is closer to 44. The reason is not fully settled, but faster early growth and higher rates of age-related disease in large breeds are both implicated.
What is the epigenetic dog age formula?
A 2020 study in Cell Systems compared DNA methylation in dogs and humans and produced the formula human_age = 16 × ln(dog_age) + 31. It is shown here as a second opinion. It was derived from Labrador Retrievers only, so it carries no size adjustment at all, and it does not work below one year.
When is a dog considered senior?
It depends on size. Giant breeds are usually treated as senior from about 7 years, large breeds 8, medium breeds 10 and small breeds 11. Senior status mainly changes the veterinary schedule: twice-yearly exams and screening bloodwork rather than annual visits.
How do I estimate the age of a rescue dog?
A vet estimates from teeth first: puppies have a full set of adult teeth by about seven months, then tartar and wear accumulate predictably. Eye lens clouding, muscle tone and greying around the muzzle refine the guess. An estimate within a year or two is usually the best available.
Does neutering or breed affect ageing?
Neutered dogs live longer on average, though the effect varies by breed and by the age at which it was done. Breed matters enormously beyond size alone: some large breeds are notably long-lived, and some small breeds are not. The size tiers here are an average, not a prediction for an individual.