Dog Age to Human Years: Full Conversion Table by Breed Size

You've heard the "multiply by 7" rule a hundred times. It's also wrong — and it gets more wrong the older (or bigger) your dog gets. A 1-year-old medium dog is developmentally equivalent to a 15-year-old human, not a 7-year-old. And a 12-year-old Chihuahua is about 64 in human years, while a 12-year-old Great Dane is closer to 93.

The reason: dogs age rapidly in their first two years, then the rate slows down — but how much it slows depends heavily on size. Small dogs live longer and age slower. Giant breeds are sprinting through life. This table gives you the actual numbers, based on the methodology the AKC and most veterinary schools use today.

How the AKC Formula Works

The American Kennel Club stopped endorsing the "multiply by 7" rule years ago. Here's what they use instead:

• Year 1: 15 human years for all breeds. A 1-year-old dog has reached sexual maturity and is roughly equivalent to a mid-teen human.
• Year 2: +9 human years (so 24 total). A 2-year-old dog is developmentally a young adult, similar to a human in their early-to-mid 20s.
• Year 3+: After age 2, each dog year adds roughly 4 human years for small breeds, 5-6 for medium breeds, 7 for large breeds, and 9-11 for giant breeds. The exact number varies by study, but the principle is consistent: bigger dogs age faster after the first two years.

The 2019 UC San Diego study that proposed the logarithmic formula (human_age = 16 × ln(dog_age) + 31) captured media attention because it incorporated epigenetic methylation data. But that formula was based on Labrador Retrievers only — applying it to a Chihuahua or a Great Dane produces misleading numbers. The tiered size-based approach below is what veterinarians actually use in practice, and it's what powers our dog age calculator.

Complete Dog Age to Human Years Conversion Table

Cells marked with "—" indicate ages that exceed the typical maximum lifespan for that breed category. Most giant breeds don't reach 12, and most large breeds don't reach 14. That's not a rule for every individual dog — some beat the odds — but it's what the breed data shows across thousands of dogs.

Why Size Matters More Than Anything Else

You can see the gap widening in the table above. At age 1, all dogs are 15 in human years. By age 7, the small breed is 44 and the giant breed is 69 — a 25-year spread. By age 10, the small breed is 56 and the giant breed is 96. That's a 40-year difference.

This happens because large dogs' cells divide more times over their lifespan to build and maintain more body mass, and each division increases the chance of replication errors that lead to aging and cancer. It's the same reason taller humans have slightly shorter average lifespans than shorter humans — the effect exists across species. For a thorough breakdown of why this happens and what you can do about it, read our guide on small breed vs large breed aging differences.

Life Stage Definitions

Know your dog's life stage and you know what to expect. An "adult" dog needs maintenance care and preventive health. A "senior" dog needs biannual vet visits and joint support. A "geriatric" dog often needs medication, mobility aids, and adjusted expectations for quality of life. If you're unsure where your dog falls, check our step-by-step conversion guide for the math behind these numbers.

The table above gives you reference points, but for an exact conversion based on your dog's actual breed and size, use our dog age calculator on the homepage — it handles the in-between years and mixed breed estimates that a table can't capture.