What is Dog Age?
The Dog Age Calculator converts your dog's age to the equivalent human age. The old rule of 'multiply by 7' is wildly inaccurate — a 1-year-old dog is sexually mature and equivalent to a 15-year-old human, not a 7-year-old.
Modern veterinary science shows that dogs age rapidly in their first two years (reaching ~24 human years by age 2), then slow down to about 3-5 human years per dog year depending on breed size. Small dogs (under 10 kg) age slower and live longer (12-16 years), while giant breeds (over 40 kg) age faster and live shorter (8-10 years).
A 2019 study from UC San Diego using DNA methylation (epigenetic clock) found the most accurate formula: human age = 16 × ln(dog age) + 31. This calculator uses a simplified version adjusted for breed size.
Formula
Modern dog age conversion: Year 1: ~15 human years Year 2: ~24 human years (9 more) Year 3+: 3-5 human years per dog year depending on size Small dogs (<10kg): ~4-5 human years per dog year Medium dogs (10-25kg): ~3.5-4.5 human years per dog year Large dogs (>25kg): ~3-4 human years per dog year Average life expectancy: Small breeds: 12-16 years (Chihuahua, Pomeranian, Dachshund) Medium breeds: 10-14 years (Beagle, Bulldog, Cocker Spaniel) Large breeds: 8-12 years (Labrador, Golden Retriever, German Shepherd) Giant breeds: 6-10 years (Great Dane, Saint Bernard, Mastiff)
How to use this Dog Age Calculator?
1. Enter your dog's age in years (use 0.5 for 6 months). 2. Select size: Small (under 10kg), Medium (10-25kg), Large (over 25kg). 3. See the human equivalent age, life stage, and breed-size life expectancy.