Free Guide
How to Tell a Dog's Age
Five signals to estimate a dog's age when you don't know their birth date.
The most accurate way to tell a dog's age is by looking at their teeth — especially in puppies, whose baby and adult teeth come in on a predictable schedule. In adult and senior dogs, combine five signals: teeth, coat, eyes, muscle tone, and behavior.
Teeth — The Most Reliable Signal
Puppies follow a fixed teething timeline (see the chart below), making teeth the most accurate way to age a young dog. In adults, the accumulation of tartar and staining gives a rough estimate; in seniors, wear and missing teeth are the giveaway.
Coat — Gray Starts at the Muzzle
Like humans, dogs typically go gray around the face first. Most dogs show a few gray hairs near the muzzle by around age 5, becoming more widespread by 7–10 years.
Eyes — Lenticular Sclerosis
In dogs 6–8 years and older, the lens of the eye can develop a slight blue-gray haze called lenticular sclerosis. It's a normal part of aging and different from cataracts, though a vet visit can help tell them apart.
Muscle & Body — Loss of Muscle Tone
Older dogs often show thinning muscle along the back and hind legs, making the spine and ribs more visible even at a healthy weight, along with a general decline in activity.
Behavior — Energy and Sleep
Puppies are high-energy and mouthy; senior dogs sleep more, rise more slowly, and may hesitate on stairs or jumps.
Teeth Age Chart
| Age | Teeth Characteristics |
|---|---|
| Birth – 2 weeks | No teeth |
| 3–6 weeks | 28 baby teeth erupting |
| 6–8 weeks | Full set of baby teeth |
| 3–4 months | Baby teeth start falling out; adult teeth emerging |
| 6–7 months | 42 adult teeth fully in |
| 1–2 years | Teeth white, little to no wear |
| 3–5 years | Tartar buildup begins |
| 5–10 years | Noticeable tartar and staining |
| 10+ years | Visible wear, possible missing teeth |
For a Precise Answer, Ask Your Vet
If you need a more exact estimate — for example, adopting a dog with no history — a veterinarian can combine a dental exam, bloodwork and a general physical assessment for a more confident age range.
These signals are general estimation guidelines, not a medical diagnosis. Individual dogs vary based on breed, genetics, diet and health history.
Frequently Asked Questions
How do you tell a dog's age by teeth?
In puppies, look at which teeth have come in — baby teeth vs. adult teeth follow a predictable timeline. In adult dogs, look at the buildup of tartar and staining; in seniors, look for wear and missing teeth.
How accurate is aging a dog by teeth?
Very accurate in puppies (often within a few weeks), but only a rough estimate range in adult and senior dogs, since diet, genetics and dental care all affect wear differently.
How can you tell if a dog is senior?
Look for a combination of signs: graying fur (especially around the muzzle), cloudy or bluish eyes, muscle loss, and reduced activity or slower movement.
What age do dogs get gray hair?
Most dogs start showing a few gray hairs around the muzzle by about age 5, becoming more noticeable by 7–10 years.