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Dog Age Calculator

Convert your dog's age into human-equivalent years by breed size, and see whether they count as a puppy, adult, or senior.

Your dog’s age

Years
Months

Calculated in your browser. Nothing is uploaded.

Breed size

Method

Human-equivalent age
24human yearsAdult
Life stage
Puppy
Growing and developing
Adult
Fully grown and active
Senior
Slowing down with age

These figures are estimates based on a breed-size chart, not a veterinary assessment. Real ageing depends on breed, weight, and health.

How to calculate your dog age in human years

  1. Enter your dog's age

    Type the age in years and months. Puppies under a year old are handled from the months field alone.

  2. Pick the breed size

    Choose small, medium, large, or giant, since larger dogs age faster and reach their senior years sooner.

  3. Read the human-year age

    The human-equivalent age and a puppy, adult, or senior label appear instantly, with no button to press.

  4. Switch method or copy

    Toggle between the size chart and the log formula, then copy a short summary to share.

Why use this tool

Human years by breed size

A size-adjusted mapping covers the first two years, then adds a fixed number of human years per dog year after that, more for larger breeds.

Puppy, adult, or senior

A life-stage label is set from the age and the breed size, so a large dog is flagged as senior earlier than a small one.

Two methods to compare

Switch between the breed-size chart and the 16 × ln(age) + 31 curve to see both estimates for the same dog.

Works for puppies too

Ages under one year map straight from the months field, so a six-month-old puppy still gets a sensible figure.

Runs entirely in your browser

Everything happens on your device. Nothing about your dog is uploaded, stored, or logged.

About this tool

This dog age calculator converts your dog's age into human-equivalent years and labels the life stage as puppy, adult, or senior. Enter the age in years and months, pick a breed size, and the result updates instantly. Small dogs and giant breeds age at very different rates, so the size you choose changes both the human-year figure and when your dog counts as a senior.

Two methods are available. The size chart uses a size-adjusted mapping for the first two years, where roughly the first year equals fifteen human years and the second brings the total to the mid-twenties, then adds a fixed number of human years for every dog year after that, more for larger dogs. The log formula uses 16 × ln(age) + 31, a curve published from a study of a single breed that rises fast in puppyhood and levels off later. It does not vary by breed size, so in that mode only the life stage reflects the size you picked.

These figures are estimates, not veterinary measurements, and real ageing depends on breed, weight, and health. Use them as a friendly guide rather than a diagnosis. If you know your dog's birthday but not the exact age, work it out first with the age calculator or the date difference tool, then enter years and months here. Everything is calculated on your device, and one click copies a short summary you can share.

Frequently asked questions

How do dog years convert to human years?
The old rule of one dog year to seven human years is too rough. This tool uses a size-adjusted chart for the first two years, then adds a set number of human years for each dog year after that, which better matches how dogs actually age.
Why does breed size change the result?
Larger dogs mature and age faster than smaller ones, so a giant breed reaches a given human-equivalent age, and its senior years, earlier than a small breed of the same dog age. The size you pick adjusts both the number and the life stage.
What is the log formula option?
It is 16 × ln(age) + 31, a curve derived from a study of one breed. It rises quickly during puppyhood and flattens with age. Because it comes from a single breed, it does not vary by size, so only the life-stage label reflects your dog size in that mode.
How is the puppy, adult, or senior label decided?
It is based on the dog age together with the breed size. Puppyhood ends later for larger breeds, while their senior stage begins earlier, so the same age can read as adult for a small dog and senior for a giant one.
Is my data uploaded anywhere?
No. Everything runs in your browser; nothing is sent to a server. The age and size you enter are never uploaded, stored, or logged.

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