Dog age calculator: dog years to human years

Enter your dog’s age and size. The calculator converts it to human years with two established methods – the DNA methylation formula by Wang et al. (2020) and the size-based chart of the American Veterinary Medical Association (AVMA) – and explains why they differ.

How it is calculated

Why “multiply by 7” is wrong

The rule of thumb “one dog year equals seven human years” does not hold up. Dogs reach sexual maturity and nearly full size within their first year, and aging slows down afterwards. The American Veterinary Medical Association (AVMA) also points out that dogs do not age at a rate of 7 human years per dog year. This calculator therefore uses two documented methods.

Method 1: the Wang et al. (2020) formula

Researchers at the University of California San Diego measured age-related DNA methylation changes in 104 Labrador retrievers and compared them with humans. The result is the formula:

Human age = 16 × ln(dog age) + 31 (ln = natural logarithm)

Example: an 8-year-old dog: ln(8) = 2.079; 16 × 2.079 = 33.3; + 31 = 64 human years. A 1-year-old dog equals 31 human years (ln 1 = 0), a 2-year-old about 42, a 12-year-old about 71 – which, according to the study, matches the life expectancy of Labradors (about 12 years) and humans (about 70 years).

Limits: the study only looked at Labradors. The authors themselves note that breeds with different lifespans could yield different age-translation functions. For puppies younger than about 2 months the formula gives no meaningful values.

Method 2: the AVMA chart by size

The AVMA published estimated human equivalents for older dogs by size (small 0–20 lbs, medium 21–50 lbs, large 51–90 lbs, giant over 90 lbs):

Dog age	small–medium	large–giant	for comparison: Wang et al.
7 years	44–47	50–56	62
10 years	56–60	66–78	68
15 years	76–83	93–115	74
20 years	96–105	120 (large)	79

The calculator uses the lower end of each range for the smaller class and the upper end for the larger class, and interpolates linearly between the chart years. Below 7 and above 20 years (giant dogs: above 15) the chart gives no values.

Why the two methods differ

The Wang formula rises steeply at first and then flattens: young dogs age biologically very fast, older dogs more slowly. Size plays no role in it. The AVMA chart only starts at 7 years and rises more steeply after that – especially for large dogs, which live shorter lives on average. That is why Wang is usually higher for younger seniors, while the AVMA chart is higher for very old and large dogs.

When is a dog a senior?

According to the AVMA, a dog is a senior in the last 25 percent of its breed’s expected lifespan. On average: small dogs at 8–11 years, medium dogs at 8–10, large dogs at 8–9 and giant dogs at 6–7 years. Older dogs benefit from more frequent veterinary checkups.

Note: all conversions are approximations and are no substitute for advice from a veterinarian.

Frequently asked questions

How old is a 1-year-old dog in human years?

About 31 human years according to Wang et al., because ln(1) = 0 and 16 × 0 + 31 = 31. A one-year-old dog is already an adult – much older than the “times 7” rule suggests.

Is one dog year really seven human years?

No. Dogs age much faster in their first years and more slowly later on. The AVMA also stresses that dogs do not age at a 7 : 1 rate.

Which method is more accurate?

Neither is exact. The Wang et al. formula is based on DNA methylation measurements, but in Labradors only. The AVMA chart is an estimate but takes size into account. Together they give a realistic range.

Why do large dogs age faster?

Large and giant breeds have a shorter life expectancy on average. The AVMA therefore places the senior age of giant dogs at 6–7 years, but at 8–11 years for small dogs.

Can I convert a puppy’s age?

From about 2 months, yes, with the Wang et al. formula – a 6-month-old dog equals about 20 human years. The AVMA chart only starts at 7 years.

Sources and legal basis

As of: 27 September 2026