🐕 Dog Age Calculator

Convert your dog's age to human years using a log-linear formula from canine epigenetic aging research — more accurate than the old 'multiply by 7' rule, since dogs age fastest when young.

Dog's Age (years)

The log-linear formula this uses

Instead of a flat multiplier, the calculator applies the curve published from DNA methylation work on canine ageing, which lines a dog's epigenetic clock up against a human one:

human years = 16 × ln(dog years) + 31

A three-year-old dog comes out at 16 × 1.0986 + 31 = 48.6. Because it is a logarithm, the early months move the number hardest and later years barely shift it: year one alone is worth 31, but the whole stretch from ten to fifteen adds only about six and a half.

Reading the curve

Dog age	Human equivalent
6 months	19.9
1 year	31.0
2 years	42.1
5 years	56.8
10 years	67.8
15 years	74.3

Enter age in years and use decimals for puppies - 0.5 is six months. Below about 0.14 years, roughly seven weeks, the formula goes negative and the tool floors the result at zero, so it is not much use on a very young puppy.

The curve was fitted on Labrador retrievers, and there is no input for size or breed. Small dogs generally outlive giant ones, so a six-year Great Dane is further along its life than the same figure suggests for a terrier. Treat this as a translation of age, not a health assessment - when a senior dog's care plan is the question, that is your vet's call.

Frequently asked questions

How old is a 3 year old dog in human years?

48.6 by this formula - 16 times the natural log of 3, plus 31. The old multiply-by-seven rule would say 21, which badly understates a dog that is already fully grown and mature.

Is the multiply by 7 rule wrong?

It is too crude to be useful. It puts a one-year-old dog at 7 human years, when that dog is past puberty and near adult size; the log formula puts the same dog at 31.

Does breed size change the answer?

Not in this calculator - it takes age only. Size matters in reality, with large and giant breeds reaching old age several years earlier than small ones, so read the figure as an average across dogs.