Author-hosted published paper, DOI 10.1016/j.cels.2020.06.006. Results and Figure 3D give human_age = 16 ln(dog_age) + 31. The sampled dogs were primarily Labrador retrievers, aged 0.1 to 16 years. Whole-year rounding and the calculator's 1 to 20 input range are specification choices; values above 16 extrapolate the formula.
Growth & age
Dog Age in Human Years
Compare dog years to human years using one published study's formula and see the age curve.
Dog age
Enter your dog's age in years.
AGE COMPARISON
Dog age comparison
Ready when you are.
Enter your dog's age, then choose Calculate dog's human age to see the comparison and curve.
For general information only, not professional advice. Check the official sources below. Use your own judgement and speak to a qualified professional before you act.
Based on official guidance
Calculated on your device
A starting point, not advice
HOW TO USE IT
Start with your details
Enter your dog's age
Use years from 1 to 20, with at most one decimal place. For example, enter 2.5 for two and a half years. Ages below one year are outside this calculator's input range.
Calculate the comparison
Choose Calculate dog's human age to see the whole-number estimate and your dog's position on the curve. Calculate again after changing the age.
Read the study limits
This is a rough comparison, not a measurement of health or life expectancy. The dashed curve above 16 years extends beyond the study's sampled ages.
Share or print
Share puts the entered age in a link that reproduces the result. Print includes the comparison, curve and study limits. Browser print can save a PDF. This tool has no device-save or calendar action.
HOW IT WORKS
What shapes your result
Human age = 16 x ln(dog age) + 31. Here ln means the natural logarithm, calculated with Math.log. The displayed estimate is rounded to the nearest whole human year.
Wang and colleagues published the study in Cell Systems in 2020. They compared DNA methylation patterns across dogs and humans. The curve rises more steeply at younger dog ages and becomes flatter as dog age increases.
The study sampled 104 dogs, primarily Labrador retrievers. This comparison does not adjust for breed or size and does not predict health or lifespan.
The study's dogs ranged from 0.1 to 16 years. This tool's specified range is 1 to 20. Values above 16 are marked extrapolations. The chart draws the unrounded formula; the selected marker follows that curve and its description uses the rounded estimate.
All country editions use one formula. The entered age stays on your device unless you share the link. Shared calculations keep that age; they do not age automatically. Editing clears the shared reference and shows an Inputs changed notice. The previous comparison stays visible until you choose Calculate again.
Read about our methodologyFAQ
Common questions
Short answers to what people ask most.
Is one dog year really seven human years?
This calculator uses a logarithmic formula from one published study. Each extra dog year does not add a fixed number of human years: the curve is steeper early on and flatter later. It remains a rough guide.
How is this formula worked out?
Multiply the natural logarithm of dog age in years by 16, add 31, then round to a whole number. The study derived the relationship by comparing DNA methylation patterns between dogs and humans. The chart shows the formula before rounding.
Does breed size change the result?
This tool has no breed or size adjustment. The research sampled primarily Labrador retrievers, and other breeds can age differently. Treat the output as a comparison rather than your dog's precise biological age.
How old is a 1 year old dog in human years?
The specified formula gives 31: ln(1) is zero, so 16 x 0 + 31 = 31. This is an estimate from a DNA-aging comparison, not a claim about a dog's temperament or maturity.
Can I use it for a dog older than 16?
The specified input range extends to 20 years. The oldest sampled dogs were 16, so results above that age extend the formula beyond the observations. Both the result and dashed chart segment identify this limitation.
Can I share or print the result?
Share creates a link with the entered age in a URL fragment, which is not sent to the host. Anyone with the link can read it. Print includes the result, chart and general disclaimer and can save a PDF through your browser. This tool has no device-save or calendar action.
Sources and checked dates
Each note explains what its source supports. Open the link to read the guidance yourself.
Confirms the natural-logarithm equation and explains the Labrador retriever study's breed limitation. Other age charts on this page are not used by this calculator.
