Dog Age in Human Years

A 1-year-old dog is roughly 31 in human years, and a 2-year-old dog is roughly 42 — not 7 and 14. The "multiply by 7" rule doesn't hold up: dogs age fast in their first couple of years and then slow down, so the ratio isn't constant. A 2020 study measured that curve directly, by comparing chemical changes to dogs' and humans' DNA over time, and fit it to a formula: human age = 16 × ln(dog age) + 31. Enter your dog's age below.

Why this formula, and where it breaks down

The formula comes from Wang et al. 2020 (Cell Systems), who tracked DNA methylation — a chemical marker that changes predictably with age — in 104 Labrador retrievers from about a month old to 16 years, and matched that curve to the equivalent human methylation curve. It captures the real shape of aging better than a fixed multiplier: fast in puppyhood, leveling off later. But it was built from Labradors only, and the paper itself notes that breeds age at different rates — a Great Dane and a Chihuahua don't share one aging curve, so treat the result as an estimate, not a breed-specific one. The formula also isn't meaningful for very young puppies (under about 2 months), where it produces a negative number — this tool shows a note instead of a nonsensical age in that range.

If the number puts your dog in the senior range

Age alone doesn't tell you what to change. But if you're wondering where to start, this site's own data points at footing and steps before diet or supplements — see thesenior-age calculatorfor whether your dog is actually in that window by size, and thefloor traction calculatorfor the most common first fix: slippery floors.

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