Dog Age Chart
Human years for dog ages 1 to 20.
Starting estimate from a published formula. Your vet knows your pet.
How to use the dog age chart
- Type a whole year from the chart, or leave 10 to see that row above the grid.
- Read the DNA figure first. The 7× figure is the other column, kept so the gap is visible.
- Use the grid for every year from 1 to 20. It is the same two formulas, not a third method.
- Months, and a puppy under a year, belong on the calculator. This grid is whole years from 1 to 20.
How to read this chart
Each row is one whole dog year. The middle column is human years from the DNA formula, 16 × ln(dog years) + 31. The right column is that year multiplied by 7. For year 10 the DNA cell is 67.8 human years and the 7× cell is 70 human years.
Read across, not down a single column. The point of printing both is the gap. At 1 year the shortcut says 7 and the DNA formula says 31. By year 10 the shortcut has caught up and then passed. Later rows keep adding 7 on the right while the DNA column adds less than that.
Months are not in the grid. A dog who is 10 years and 4 months is not row 10 and not row 11. Use the calculator for the fraction. Puppies under six months are clamped on the DNA formula, so they are a poor fit for this grid.
Where the 7× rule came from as a habit
Multiply by seven is the rule people remember because the arithmetic is one step. It treats the first year the same as the tenth. That is why a one-year-old dog comes out 'seven' and a ten-year-old comes out 'seventy', as if aging were a straight line.
This chart does not give the shortcut a founding year or an author. The right-hand column is a straight line, and the DNA column is not.
The DNA formula comes from a 2020 study of blood samples from 104 dogs, mostly Labrador retrievers, aged four weeks to 16 years. It was fit mostly on Labradors, and it is a rough guide in the first year.
What you can and cannot take to the clinic
You can say: at 10 years the DNA figure is 67.8 human years and the 7× figure is 70 human years, and the formula was fit on Labradors. You cannot say the chart has declared the dog a senior. The calculator shows a life-stage line from the 2019 AAHA definitions, and that line still does not name a senior birthday.
Two dogs of the same age share a row on this page even when their lives are not the same length. Large breeds often live shorter lives. That fact is not turned into a third column. The vet who can see the dog is the one who can call the stage.
Dog years 1 to 20
| Dog year | DNA formula | 7× rule |
|---|---|---|
| 1 | 31 | 7 |
| 2 | 42.1 | 14 |
| 3 | 48.6 | 21 |
| 4 | 53.2 | 28 |
| 5 | 56.8 | 35 |
| 6 | 59.7 | 42 |
| 7 | 62.1 | 49 |
| 8 | 64.3 | 56 |
| 9 | 66.2 | 63 |
| 10 | 67.8 | 70 |
| 11 | 69.4 | 77 |
| 12 | 70.8 | 84 |
| 13 | 72 | 91 |
| 14 | 73.2 | 98 |
| 15 | 74.3 | 105 |
| 16 | 75.4 | 112 |
| 17 | 76.3 | 119 |
| 18 | 77.2 | 126 |
| 19 | 78.1 | 133 |
| 20 | 78.9 | 140 |
Whole years only. The DNA column is 16 × ln(year) + 31. The 7× column is the popular shortcut.
Tips and common mistakes
- Do not average the two cells. They are different rules sitting next to each other.
- Row 1 is not 'a human child of 7'. The DNA cell is the one from the 2020 study.
- If the dog is 20, you are at the bottom of the grid. The formula still runs past 20 on the calculator, but this chart stops.
When to call your vet
- You needed a senior label, a vaccine interval or a diet change, and the chart has no band for that.
- Stiffness, thirst, weight or energy changed. A row on a chart does not explain those.
- Someone quoted a table with different steps for toy and giant dogs. Ask the clinic which paper they are using before you adopt it.
- The dog is under a year. This grid is the wrong tool.
Frequently asked questions
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.
At what age is a dog senior?
Not a year on this chart. The calculator shows an AAHA 2019 life-stage line, and that line still does not name a senior birthday. Ask your vet.
How are the numbers worked out?
DNA column: 16 × ln(dog years) + 31, rounded to one decimal. 7× column: the year times 7. Year 1 is 31.0 and 7. Year 10 is 67.8 human years and 70 human years when the box is set to 10.
Why is year 1 so far from 7?
Because the shortcut counts the first year as seven human years, and the DNA formula does not. The early years move faster on the DNA column. That gap is why both columns are on the page.
Can I use this for a 10-year-old and a 10-month-old the same way?
Only the 10-year-old belongs on row 10. Ten months is under a year. The calculator clamps the DNA formula below half a year and will take the extra months. This chart will not.