Pet Age In Human Years Calculator

Work out pet age in human years instantly with clear inputs, formula shown and shareable results.

About Pet Age In Human Years Calculator

This follows the veterinary convention: the first year counts as about 15 human years, the second adds 9, and each year after that adds 4 to 6 depending on species and breed size. The flat seven years per dog year rule is badly wrong at both ends of a dog's life, which is why the staged version is used clinically.

Formula

Conversion

year 1 = 15 human years; year 2 adds 9; each later year adds 4 to 6 by size

Worked example

With the default values below, Pet Age In Human Years Calculator returns Equivalent human age of 44.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Pet's ageminimum 0.1 years: 6 years
Species and sizeone of Dog, small breed, Dog, medium breed, Dog, large breed, Cat: Dog, medium breed

Results

Equivalent human age: 44.0 years
Life stage: Adult
Human years added per pet year after age two: 5
Human years the next pet year adds: 5

Step by step

1Values used
2Conversion
3Equivalent human age= 44.0 years
4Life stage= Adult
5Human years added per pet year after age two= 5
6Human years the next pet year adds= 5

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Pet Age In Human Years figure worked out?

year 1 = 15 human years; year 2 adds 9; each later year adds 4 to 6 by size. This follows the veterinary convention: the first year counts as about 15 human years, the second adds 9, and each year after that adds 4 to 6 depending on species and breed size.

Why does this matter?

The flat seven years per dog year rule is badly wrong at both ends of a dog's life, which is why the staged version is used clinically.

What do I need to enter?

Enter pet's age, species and size. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.