Dog Age Calculator
Dog years to human years, two methods.
Starting estimate from a published formula. Your vet knows your pet.
How to use the dog age calculator
- Enter years and extra months. Fourteen months is read as one year and two months, not as a fourteenth month of year zero.
- Read the DNA formula figure first. The 7× figure sits beside it so you can see the gap.
- Use the table further down for whole years from 1 to 15. It is the same formula, not a second method.
- If the age is under six months, the DNA line is clamped. The note under the result says when that happened.
Two methods, side by side
People ask for dog years in human years because a single number feels like an answer. It is not a medical age. This page shows two calculations.
The DNA formula (16 × ln(dog years) + 31) comes from a 2020 study of blood samples from 104 dogs, mostly Labrador retrievers, aged four weeks to 16 years. It is a better guide than the 7× rule, but it was fit mostly on Labradors and is less exact in the first year, so treat it as a rough guide. Dog years below 0.5 are raised to 0.5. That floor is this site's display choice; the study starts at four weeks. The result says when the floor was used. The study is Wang and colleagues, Cell Systems, 2020.
The second line is the popular 7 × age rule. At 5 years the DNA line is 56.8 human years and the 7× line is 35 human years. The 7× rule counts every year as seven human years, including the first, so a one-year-old comes out at 7 rather than about 31. It is here so the gap is visible. It is not a veterinary standard.
Only those two calculations are on this page. The study does not give a separate yearly step for every breed, so none is printed.
What changes as the years add up
This page does not print a senior age. The life-stage line under the dog's age follows the 2019 AAHA definitions. Under six months it says puppy. From six months to nine months it may still be a puppy or already a young adult, because rapid growth stops somewhere in that window. From nine months until three years it says young adult. From three years through four years it may be a young adult or a mature adult. After four years it says mature adult or senior, and it does not pick which one. A guessed 'senior at 6' would look like guidance, and it would be wrong for some dogs.
On the DNA formula, the early years move faster than the later ones. The jump from 1 to 2 dog years is large. Later years add less than seven. The table shows the DNA column and the 7× column pulling apart. That comparison is the point of the page.
Under about a year the formula is the wrong tool. Inputs below 0.5 years are clamped, and the result says so. A young puppy is not '31 human years'.
How to read the number you take to the clinic
Say both figures: 56.8 human years on the DNA formula and 35 human years on the 7× rule, for a dog of 5 years. The DNA number is a human-equivalent age in the shape of a Labrador's life, not a promise about your dog. The life-stage line beside those figures is a separate sentence from the 2019 definitions. It is not a medical age either.
Months are added as twelfths of a year before the logarithm. The table uses whole years from the same formula. Neither number is a lifespan, a diagnosis, or a reason to change food or vaccines on its own.
Human-equivalent age by dog year
| Dog's age | DNA formula | 7× rule |
|---|---|---|
| 1 year | 31 human years | 7 human years |
| 2 years | 42.1 human years | 14 human years |
| 3 years | 48.6 human years | 21 human years |
| 5 years | 56.8 human years | 35 human years |
| 7 years | 62.1 human years | 49 human years |
| 10 years | 67.8 human years | 70 human years |
| 12 years | 70.8 human years | 84 human years |
| 15 years | 74.3 human years | 105 human years |
Whole years, no extra months. The DNA formula was fit on 104 dogs, mostly Labrador retrievers, and is a rough guide, especially in the first year.
Tips and common mistakes
- Do not average the two figures. They answer different questions, and only the DNA line comes from the 2020 study.
- The DNA formula was fit mostly on Labrador retrievers. A Great Dane and a Chihuahua of the same age get the same figure here.
- Check the typing if the age is over 30 years, and read the clamp note for a puppy under a year.
When to call your vet
- The life-stage line says mature adult or senior, and you need a yes or no. That line does not pick a senior birthday. Ask your vet.
- Appetite, drinking, weight, stiffness or energy have changed. An equivalent human age does not explain those.
- You are choosing vaccine intervals, a diet or a pain plan from the number alone. Those decisions need an exam.
- The dog is a puppy and someone has told you the first year equals 15 or 31 or 7. Bring the disagreement to the vet rather than picking the largest number.
Frequently asked questions
Is 1 dog year really 7 human years?
No. The 7× rule is on this page only so you can see it fail. At 5 it says 35 human years. The DNA formula says 56.8 human years. One year of dog age is not seven human years at the start or later.
Does it change with size?
This formula does not use the dog's size. It was fitted on 104 dogs, mostly Labrador retrievers, so it is a rough guide for very small or very large dogs.
What is the DNA-based formula?
Human years = 16 × ln(dog years) + 31. Ages under 0.5 years are raised to 0.5, a display choice on this site. The study, described above, used 104 dogs, mostly Labrador retrievers. The 7× rule is the comparison, not a standard.
How old is a 5-year-old dog in human years?
On the numbers this page opens with, a 5-year-old is 56.8 human years by the DNA formula and 35 human years by the 7× rule. Adding months moves the DNA figure slightly. The life-stage line for that age names two stages and does not pick a senior birthday.