Dog Age (Allometric) Calculator
The old "one dog year equals seven human years" rule does not match how dogs actually age: they mature very fast at first, then slow down. A 2020 epigenetic study proposed a logarithmic conversion that captures this. This calculator applies that formula, human-equivalent age equals 16 times the natural log of the dog's age plus 31, returning the human-equivalent age for any dog age you enter. The two constants are user-editable so you can substitute breed-specific values if you have them.
Allometric age formula
Human age = multiplier * ln(dog age) + offset
Default: human age = 16 * ln(dog age) + 31
ln is the natural logarithm (base e). The formula is defined for dog ages greater than zero. The constants 16 and 31 come from the 2020 epigenetic-clock study of Labrador retrievers.
Worked example
For a 4 year old dog: human age = 16 * ln(4) + 31 = 16 * 1.38629 + 31 = 22.18 + 31 = 53.18 human-equivalent years.
Dog age formula: frequently asked questions
What is the allometric dog-age formula?
A 2020 study of DNA methylation in Labrador retrievers proposed that a dog's human-equivalent age is 16 times the natural logarithm of the dog's age in years, plus 31. This non-linear curve captures rapid early ageing that slows over time, unlike the old multiply-by-seven rule.
Why is the natural logarithm used?
Dogs age very quickly in their first two years and then more slowly. A logarithmic curve matches this pattern: it rises steeply at low ages and flattens out, which the constant multiply-by-seven approximation cannot do.
Does this apply to all dog breeds?
The published formula was derived from Labrador retrievers, so it is best treated as a general guide. Small and large breeds age at different rates, with giant breeds typically ageing faster. Use it as an estimate, not a precise figure for every breed.
Official sources
- U.S. National Institutes of Health, National Library of Medicine: PubMed (epigenetic-clock and DNA-methylation ageing research).
- The natural-logarithm curve is a standard allometric form; the constants are the published study values.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.