Worldwide
Dog age calculator
Most people grew up being told to multiply a dog's age by seven to get its age in human years.
This uses the 2020 epigenetic-clock formula, human age = 16 x ln(dog years) + 31, which fits how a dog actually ages: very fast at first, then slowing.
That rule is tidy but wrong, and it has been wrong for a long time. A dog is not one seventh of the way through a human life at twelve months; a year-old dog is closer to a person in their early thirties, already past puppyhood and able to breed. This calculator drops the seven-times shortcut and uses the formula a team of geneticists published in 2020 after comparing how DNA changes with age in dogs and people. Put in your dog's age in years and it returns a human-equivalent age that rises fast in the early years and then slows, which is how dogs really age. It also names the life stage and, for interest, shows what the old rule of thumb would have said so you can see how far off it was.
How it works
- Enter your dog's age in years; part years are fine, so a dog of two and a half goes in as 2.5.
- For a dog aged one or more the calculator applies the 2020 epigenetic formula, human age = 16 times the natural log of the dog's age, plus 31.
- It rounds the result to a whole number of human years and labels the life stage, from puppy through to senior.
- For comparison it also shows the discredited "times seven" figure, so you can see why that old guess flatters a young dog and shortchanges an old one.
human age = 16 x ln(dog years) + 31, for dogs aged one year and older
The natural logarithm captures the way a dog ages quickly when young and then more slowly. At one year the log is zero, so the result is the anchor value of 31 human years. Each time the dog's age multiplies, the human figure rises by the same fixed step rather than by a fixed amount, which bends the line into the curve seen in real ageing. The figure is rounded to a whole year for display.
- dog years
- your dog's actual age in years
- ln
- the natural logarithm, base e
- 31
- the human age that a one-year-old dog maps to
- 16
- the scaling step the study fitted between the two species
Dog age to human age, modern formula
| 1 year | about 31 human years | already an adult, not a child |
| 2 years | about 42 human years | full maturity |
| 5 years | about 57 human years | middle age for most breeds |
| 10 years | about 68 human years | a senior dog |
| 15 years | about 74 human years | a long life for many breeds |
Worked example
A four-year-old dog: the formula gives 16 times the natural log of 4, which is about 22.2, plus 31, so roughly 53 human years. The old rule would have said 28. By ten years the formula reaches about 68 human years, while the seven-times rule lags at 70 only because its straight line finally catches up; in the early years the two diverge sharply.
Key facts
- A one-year-old dog is roughly a 31-year-old person, not a child, which is why the times-seven rule fails worst when dogs are young.
- The 2020 formula comes from comparing DNA methylation, a chemical ageing marker, in dogs and humans.
- Ageing is fast in the first two years, then slows, so the human-equivalent curve rises steeply early and flattens later.
- Small breeds generally outlive giant breeds, so two dogs of the same age can be at quite different life stages.
Tips
- Enter a part year for a young dog, since a few months make a real difference in the first two years.
- Use the life-stage label, not just the number, to judge when to switch food or raise how often you visit the vet.
- For a giant breed treat the figure as slightly young, and for a small breed as slightly old, then ask your vet.
- Record your dog's birthday or adoption-estimate date so the age you enter stays accurate year to year.
Frequently asked questions
Why is the old "multiply by seven" rule wrong?+
It assumes a dog ages at a steady pace across its whole life, which it does not. Dogs grow up very quickly in the first two years, reaching social and physical maturity, then age more gradually. A flat multiplier cannot capture that curve, so it badly overstates the age of a young dog and understates an old one.
Where does the formula come from?+
A 2020 study in the journal Cell Systems by Wang and colleagues at the University of California compared chemical marks on DNA, called methylation, in Labrador retrievers and in humans. The marks change with age in a similar way across both species, and the team fitted the translation human age = 16 ln(dog years) + 31 to line the two clocks up.
Does breed or size change the answer?+
It does in real life, though this formula does not adjust for it. Small breeds tend to live longer and stay "younger" for their years, while giant breeds age faster and have shorter lives. The published formula was built mainly on a single breed, so read the figure as a good general guide and let your vet weigh in on your dog's breed and health.
What about a puppy under one year old?+
The formula is built for dogs aged one and up, because the natural log of a number below one turns negative. For a puppy the tool shows a rough figure based on a first year worth about 15 human years, but development in those months is so rapid that no single number captures it well.
Is this a substitute for a vet check?+
No. A human-equivalent age is a fun and useful frame for thinking about your dog's life stage, but it tells you nothing about that individual animal's health. Weight, dental condition, joints and organ function all matter more, and only a veterinary exam can assess them.
Things to watch
- This is a general model fitted mainly on one breed; it does not account for your dog's breed, size or health.
- A human-equivalent age is not a health assessment. Only a veterinary examination can judge how well an individual dog is ageing.
Sources
- Quantitative translation of dog-to-human aging by conserved DNA methylation clocks · Cell Systems (Wang et al., 2020)
- How to determine your dog's age · American Kennel Club
Last updated: 2026
This is an estimate for general guidance, not financial, tax, legal or medical advice. Figures can change and individual circumstances vary. Always confirm with the official sources listed before making decisions.
Built and maintained by Vikas Dulgunde. Editorial standards.