Dog Age Calculator
Your dog's age in human years — the real curve, not the ×7 myth.
How this is calculated
human years = 16 × ln(dog years) + 31 (UCSD 2019, dogs ≥ 1 year)
Worked example (the default): a 5-year-old dog is 16 × ln(5) + 31 ≈ 57 human years — while the ×7 myth says 35. The curve is steep early (1 year ≈ 31, 2 years ≈ 42) then flattens (10 years ≈ 68, 15 years ≈ 74), matching what the molecular clocks show: dogs front-load their aging.
Life stages by breed size
| Stage | Small (<10 kg) | Medium (10–25 kg) | Large (25–45 kg) | Giant (>45 kg) |
|---|---|---|---|---|
| Adult | 1–8 yrs | 1–7 yrs | 1–6 yrs | 1–5 yrs |
| Senior from | ~9 yrs | ~8 yrs | ~7 yrs | ~6 yrs |
| Typical lifespan | 12–16 yrs | 10–14 yrs | 9–12 yrs | 7–10 yrs |
The formula is Labrador-derived (a large-ish medium breed); shift your reading younger for small dogs and older for giants. Whatever the number says, the vet's senior-checkup schedule for your dog's size band is the version with medical teeth.
Frequently asked questions
Where does the formula come from?
A 2019 University of California San Diego study compared DNA methylation ("epigenetic clocks") in Labradors and humans, yielding human age ≈ 16 × ln(dog age) + 31. It replaces the ×7 myth with actual biology: dogs mature explosively early, then age slower.
Why does a 1-year-old dog come out at 31?
Because a one-year-old dog really is a young adult — sexually mature, fully grown in small breeds — which maps to roughly a human's late 20s to early 30s on the molecular clock. The old ×7 rule calling it a 7-year-old child was the myth's biggest failure.
Does breed size matter?
Substantially — the study was Labrador-based, and size shifts the curve: small breeds mature slightly faster early but live longer (a 10-year-old Chihuahua is younger, biologically, than a 10-year-old Great Dane — giant breeds can be seniors by 6). The table below gives the size-band picture vets actually use.
Is the ×7 rule completely useless?
For mid-life, medium-size dogs it lands vaguely close, which is how it survived a century. It fails badly at both ends: it calls a 1-year-old dog a child (wrong — young adult) and an 16-year-old dog 112 (wrong — around 75). The log curve fixes both ends.