How to Calculate Dog Years
Multiplying by seven is easy, but it misses the two things that matter most: dogs age very fast early in life, and large dogs pull ahead of small dogs after midlife. FurStage keeps both methods visible so you can see the difference instead of treating one number as universal.
The size-based method (AVMA)
The default calculator uses the AVMA size-based table. Ages 1–5 are the same for every dog size; after that, medium, large, and giant dogs climb faster than small dogs. That is why a 10-year-old small dog is about 56 human years, while a 10-year-old giant dog is about 79.
Examples from the FurStage AVMA table
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 5 years | 36 | 36 | 36 | 36 |
| 10 years | 56 | 60 | 66 | 79 |
| 16 years | 80 | 87 | 99 | 121 |
This is the practical reason size matters: the gap is zero at age five, then reaches 23 human years by age 10 and 41 human years by age 16 between small and giant dogs.
The science method (UCSD 2020)
The UC San Diego formula, human_age = 16 × ln(dog_age) + 31, models DNA methylation in dogs. It is useful for comparing biological aging, especially around early adulthood, but it does not adjust for size. FurStage keeps it as an optional toggle rather than replacing the AVMA table.
Which result should you use?
Use the AVMA result for care planning and size-aware life-stage context. Use the UCSD result when you want the research formula. For year-by-year values, open the dog years to human years chart; for care timing, jump to your dog’s life stage.
Sources and evidence
These references support the health and life-stage claims on this page. Guidelines inform care planning; studies explain specific methods; neither replaces advice from your veterinarian.
- Peer-reviewed study2020Quantitative Translation of Dog-to-Human Aging by Conserved Remodeling of the DNA Methylome
Cell Systems via PubMed Central
- Official reference2020NHGRI Researchers Reframe Dog-to-Human Aging Comparisons
National Human Genome Research Institute
- Veterinary guideline20192019 AAHA Canine Life Stage Guidelines
American Animal Hospital Association
General guidance only — not veterinary advice and not for emergencies. Consult your vet for any health decision.
Call your vet now if your pet has trouble breathing, collapses, has severe pain, repeated vomiting, seizures, heavy bleeding, or suddenly cannot stand.
Frequently asked questions
- Is 1 dog year 7 human years?
- No. The ×7 rule is a myth. Dogs mature much faster in their first two years, then aging slows — and larger breeds age faster than small ones.
- What is the most accurate dog age formula?
- For most owners the AVMA size-based table is the practical standard. The 2020 UC San Diego epigenetic formula (16·ln(age)+31) is the science-backed alternative.