the science

Not all years are created equal.

Forget the "multiply by 7" myth. Modern veterinary science uses size-adjusted formulas backed by decades of research.

The 7-year myth.

The old rule of "1 dog year = 7 human years" was a rough estimate with no scientific basis. It assumed all dogs age at the same rate regardless of breed or size — which simply isn't true.

Size matters.

Smaller dogs mature faster but age slower, living 15–20 years on average. Giant breeds age rapidly after year 2 and rarely exceed 10 years. Our calculator uses 5 size categories with different aging coefficients for each.

Backed by research.

We use the AVMA (American Veterinary Medical Association) guidelines combined with the UCSD epigenetic clock formula: Human Age = 16 × ln(Dog Age) + 31. Two methods, one accurate result.

Old method
5 × 7 = 35
Same for all dogs
vs
Our method
5 yr old Chihuahua = 36
5 yr old Great Dane = 40
Breed & size adjusted
reference

Dog age chart.

A comprehensive comparison of dog years to human years across all size categories. Smaller dogs generally live longer but age faster in the first two years.

Dog age Toy Small Medium Large Giant
≤15 lbs 16–30 lbs 31–50 lbs 51–100 lbs >100 lbs
1 year 15 15 15 12 12
2 years 24 24 25 19 19
3 years 28 28 30 26 26
4 years 32 32 35 33 33
5 years 36 36 40 40 40
6 years 40 40 45 47 47
7 years 44 44 50 54 54
8 years 48 48 55 61 61
9 years 52 52 60 68 68
10 years 56 56 65 75 75
11 years 60 60 70 82 82
12 years 64 64 75 89 89
13 years 68 68 80 96 96
14 years 72 72 85 103 103
15 years 76 76 90 110 110
16 years 80 80 95 117 117

* Based on AVMA (American Veterinary Medical Association) guidelines and peer-reviewed veterinary research. Individual results may vary based on breed, genetics, and health.