Dog Age Calculator — Convert Dog Years to Human Years

The “multiply by 7” rule is a myth. Enter your dog’s age and size for an accurate human-age equivalent using vet-approved, size-adjusted formulas — plus the science behind the numbers. Free.

Dog Age Calculator — Convert Dog Years to Human Years

Dog Age Calculator: Dog Years to Human Years

Forget “multiply by 7.” Enter your dog’s age and size for a vet-approved human-age equivalent — plus the real science behind dog aging.

🐕Smallunder 20 lbs
🐕‍🦺Medium20–50 lbs
🦮Large51–90 lbs
🐩Giantover 90 lbs
Your dog’s human-age equivalent
— human years
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🔬 Epigenetic age (the science)

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UC San Diego formula: 16 × ln(dog years) + 31. Based on 2019 DNA-methylation research — a 1-year-old dog scores 31, because dogs age fastest in their first year.

📏 Size-adjusted vet chart

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First year = 15 human years, second = 9 more, then every year counts per size. Bigger dogs age faster after year two.

Life journey

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Birth——

Estimates based on widely used veterinary age charts and the published epigenetic aging formula. Individual dogs vary by breed, health, diet, and lifestyle — your vet knows your dog best.

100% private

Everything runs in your browser. No data about your pet is collected or sent anywhere.

No signup

No account, no email, no app to install. Just enter age and size.

Free forever

Calculate for every dog in the family, as often as you like.

How to use the dog age calculator

  1. 1
    Enter your dog’s age

    Years plus any extra months — a 4-year-6-month dog is converted more precisely than “4” alone.

  2. 2
    Pick your dog’s size

    Choose by expected adult weight. For mixed breeds, use the weight your vet expects at full growth.

  3. 3
    See two science-backed ages

    Get the size-adjusted vet-chart age, the epigenetic formula age, your dog’s life stage, and where they are in their expected lifespan.

Why this beats “multiply by 7”

Size actually matters

A 5-year-old Great Dane and a 5-year-old Chihuahua are at very different life stages. This calculator adjusts for that.

Real aging science included

See the UC San Diego epigenetic formula result next to the classic vet chart — the actual research, not a folk rule.

Know their life stage

Puppy, adult, senior, or geriatric — staged by size, so you know when to shift food, exercise, and vet checkups.

Lifespan perspective

A visual life-journey bar shows roughly where your dog is in their expected lifespan for their size.

Better vet visits

Knowing your dog’s true life stage helps you ask the right questions at checkups — senior screening starts earlier for big dogs.

Private and instant

No accounts, no tracking — the math happens on your device in a fraction of a second.

Dog age questions, answered

Is the “multiply by 7” rule true?
No — it is a myth dating back decades, probably from comparing average human and dog lifespans. Real aging is front-loaded: a 1-year-old dog is roughly equivalent to a human teenager, not a 7-year-old child. Dogs mature extremely fast in their first two years, then aging slows down. Any single multiplier misses this completely.
What is the UC San Diego epigenetic formula?
In 2019, researchers in Trey Ideker’s lab at UC San Diego published a study in the journal Cell Systems comparing DNA methylation — chemical marks on DNA that change with age — in Labrador retrievers and humans. They derived the formula human age = 16 × ln(dog age in years) + 31. It captures a real biological insight: a 1-year-old dog is already about 31 in human years, while aging slows later (a 4-year-old dog scores about 53, a 12-year-old about 71). It was developed on Labradors, so it fits medium-to-large breeds best.
Why does my dog’s size change the answer?
Large and giant breeds age faster and live shorter lives — a Great Dane is senior around age 5–6, while a Chihuahua may not be senior until 10+. Small dogs also mature slightly faster in year one but then age more slowly. The size-adjusted chart reflects this: after age 2, each dog year counts as 4 human years for small dogs, 5 for medium, 6 for large, and 7 for giant breeds.
When is my dog considered a senior?
It depends on size: roughly age 5–6 for giant breeds, 6–7 for large breeds, 7–8 for medium breeds, and 8–10 for small breeds. The calculator above stages your dog automatically. Senior status matters — it is when vets typically recommend twice-yearly checkups, senior bloodwork, and diet adjustments.
Which number should I trust — the vet chart or the epigenetic formula?
Both are legitimate and they usually land close together. The vet chart is the practical standard vets and pet organizations use day to day, tuned by size. The epigenetic formula is grounded in molecular biology but was calibrated on one breed. This calculator shows you both so you can see the full picture.
How old is my puppy in human years?
Puppies age astonishingly fast. On the vet chart, a 6-month-old puppy is already about 7–8 in human years, and by their first birthday they are roughly 15 — developmentally similar to a human teenager. That is why training and socialization in the first year matter so much: it is their entire childhood compressed into months.
What about mixed-breed dogs?
Use the adult weight your vet expects — size predicts aging rate better than breed labels do. If you are unsure, pick the closest size category; being one category off shifts the result by only a year or two in most cases.

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