Date & Time · Guide
Dog Age Chart: Dog Years to Human Years
Forget multiplying by seven. Dogs age fast at first, then slow down — and big dogs age faster than small ones.
Want the answer for your own numbers? Use the free Age Calculator — it does every step below for you.
Why "one dog year = seven human years" is wrong
The seven-year rule is simple, but it does not match how dogs grow. A one-year-old dog can have puppies and is fully grown. A seven-year-old child cannot. Dogs race through childhood in their first two years, then age more slowly. Size matters too: a Great Dane is "old" years before a Chihuahua.
Dog age chart in human years
This chart uses a widely used vet rule of thumb: the first year equals about 15 human years, the second adds about 9, and each year after adds about 4 (small dogs), 5 (medium) or 6 (large).
| Dog's age | Small (under 20 lb) | Medium (21–50 lb) | Large (over 50 lb) |
|---|---|---|---|
| 1 | 15 | 15 | 15 |
| 2 | 24 | 24 | 24 |
| 3 | 28 | 29 | 30 |
| 4 | 32 | 34 | 36 |
| 5 | 36 | 39 | 42 |
| 6 | 40 | 44 | 48 |
| 7 | 44 | 49 | 54 |
| 8 | 48 | 54 | 60 |
| 9 | 52 | 59 | 66 |
| 10 | 56 | 64 | 72 |
| 11 | 60 | 69 | 78 |
| 12 | 64 | 74 | 84 |
| 13 | 68 | 79 | 90 |
| 14 | 72 | 84 | 96 |
| 15 | 76 | 89 | 102 |
| 16 | 80 | 94 | 108 |
So a 7-year-old dog is roughly 44 to 54 in human years. An 11-year-old is about 60 to 78. A 14-year-old is about 72 to 96 — truly elderly for a big breed.
Work it out yourself
The chart follows a simple rule you can use for any age:
Human age = 24 + (dog age − 2) × k
k = 4 for small dogs, 5 for medium dogs, 6 for large dogs. Use it from age 2 onward.
A 10-year-old dog
Small: 24 + 8 × 4 = 56. Medium: 24 + 8 × 5 = 64. Large: 24 + 8 × 6 = 72.
About 56 to 72 in human years, depending on size
The DNA-based formula
In 2020, researchers at the University of California San Diego compared chemical changes on DNA in dogs and people. They proposed this formula:
Human age ≈ 16 × ln(dog age) + 31
"ln" is the natural logarithm. It gives a 1-year-old dog a human age of 31, a 4-year-old about 53, and a 10-year-old about 68. It was built from Labrador retrievers, so treat it as a curiosity for other breeds.
Chart vs DNA formula side by side
The two methods disagree most for young dogs. The DNA formula makes young dogs “older” and old dogs “younger”:
| Dog’s age | Chart, medium dog | DNA formula |
|---|---|---|
| 1 | 15 | 31 |
| 2 | 24 | 42 |
| 4 | 34 | 53 |
| 6 | 44 | 60 |
| 8 | 54 | 64 |
| 10 | 64 | 68 |
| 12 | 74 | 71 |
| 14 | 84 | 73 |
Neither is a precise measurement. The chart is better for everyday use because it accounts for size; the DNA formula is mainly a research finding.
How to find your dog's exact age
Know your dog's birthday? The age calculator gives the exact age in years, months and days. Then read across the chart. For rescue dogs, a vet can estimate age from teeth, eyes and joints.
When is a dog a senior?
- Small breeds: often around 10 to 12 years.
- Medium breeds: around 8 to 10 years.
- Large and giant breeds: as early as 6 to 8 years.
Many vets suggest check-ups every six months once a dog reaches its senior years, because problems develop faster in dog time.
Signs your dog is getting older
- Grey hair around the muzzle and eyes.
- A bluish, cloudy look to the eyes.
- Stiffness after rest, or slowing down on walks and stairs.
- Sleeping more and playing less.
- Dental problems, weight gain or weight loss.
- Changes in hearing, behaviour or toilet habits.
Many of these are normal ageing. Sudden changes are not — mention them to your vet promptly.
Frequently asked questions
Roughly 44 for a small dog, 49 for a medium dog and 54 for a large dog. Bigger breeds age faster, so the same birthday means a different stage of life.
No. Dogs age very fast in their first two years, reaching about 24 human years by age 2, then more slowly. Large breeds also age faster than small ones.
Roughly 56 for a small dog, 64 for a medium dog and 72 for a large dog, using the size-based chart. The DNA-based formula puts any 10-year-old dog at about 68.
Generally, yes. Large and giant breeds age faster and reach their senior years sooner, while many small breeds live well into their teens. Individual health, genetics and care all play a part too.
Sources and further reading
- AVMA — Senior pets — how and when dogs age
- Wang et al., Cell Systems (2020) — the epigenetic dog-to-human age formula
- AVMA — Senior pets — when pets are considered senior and what care changes