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Disclaimer

Pet Human Years publishes estimates for fun and general information. It is not veterinary advice.

Not a vet, and not a substitute for one

Nothing on this site is veterinary, medical, or other professional advice, and nothing here creates a veterinarian–client–patient relationship. The calculator, charts, life stages, breed notes, and articles do not examine your pet. They do not diagnose illness, predict disease, recommend treatment, set a medication dose, plan a vaccine schedule, or prescribe a diet.

If your pet is hurt, in pain, not eating, struggling to breathe, or you are worried about their health or aging, contact a veterinarian or an emergency clinic. Do not wait on a number from this site.

What a “human year” is

A human-year figure is a rough comparison, so you can picture a pet’s age next to a person’s. It is not a biological identity. A dog that “is 47” has not lived a 47-year-old human life, and the number does not say how that dog feels, what care they need, or how long they have left.

Your pet is not the average

The math describes typical patterns, not one animal. Genetics, actual weight, breed mix, sex, whether the pet is neutered, diet, exercise, dental health, and disease all change how an individual ages. Two pets of the same age and breed can be in very different shape. A result here cannot tell those two apart.

Size, breed, and lifespan

For dogs, the vet chart depends on size: small is 20 lb or less, medium is 21–50 lb, large is 51–100 lb, and giant is over 100 lb. Pick the band that matches the dog in front of you. The wrong band changes the result. If you do not choose a size, we assume a medium dog, and the result says so.

A breed page uses a typical adult weight to choose that size band, and a published range for life expectancy. Those are averages for the breed, not a measurement of your dog. A dog who is heavier or lighter than the usual range should be read on the size that matches their weight, not on the breed label. Mixed-breed and “not sure” choices are the same kind of estimate.

Cat results do not change by breed. Every cat on this site follows one curve. A breed page for a cat still uses that curve. The lifespan range on a breed page is a published typical range, not a prediction of how long that cat will live.

Life expectancy is not a deadline and not a promise. Plenty of pets live longer than the range, and some do not reach it. A senior label is a guideline for life stage, not a finding that your pet is elderly or unwell.

Three methods, on purpose

The default is a size-based chart of the kind veterinary sources publish. We fill in the months between the yearly points, so a result for 18 months is an estimate between the one-year and two-year figures, not a separate clinical measurement. Under one year we use a first-year curve. The details and sources are on how pet age is calculated.

The DNA formula comes from a 2020 study of Labrador Retrievers. It applies to dogs only, it is not defined under one year, and it does not adjust for size. It is not a result for cats, for other breeds, or for a mixed breed, even when we can still show the number for comparison.

The ×7 rule is the old shortcut of multiplying age by seven. We show it because people ask. It is wrong at almost every age. Seeing it next to the vet chart is the point. It is not a recommendation.

Other websites, posters, and clinics use different charts. A different number does not mean either result is a measurement of your pet. We simplify published sources, and a simplification can leave out a caveat from the original.

Ages, birthdays, and rounding

Whole years on the charts are the chart’s yearly points. The calculator rounds the displayed human-year number. “I know the birthday” counts completed months from the date you enter, using your browser’s calendar. It can be a month off around month boundaries, and it does not know anything about the pet beyond that date.

Very large human-year numbers, including ages past a typical lifespan, are the formula carried forward. Treat them as a rough extrapolation. They are not a record of a pet who has lived that long.

What this site is not for

Do not use these pages to decide any of the following:

We are not the American Kennel Club, the American Veterinary Medical Association, the American Animal Hospital Association, the American Association of Feline Practitioners, the University of California San Diego, or the authors of the studies we cite. They have not reviewed or endorsed this site.

Sharing a result

A share link can include a pet name in the address. Anyone you send the link to can see that name, and so can anyone they forward it to. Do not put a person’s name, phone number, address, or any other private detail in that field. The age on the shared page is the same estimate as everywhere else.

Advertising and other sites

We may show third-party ads. An ad is not our advice, and we do not check or endorse the advertiser’s claims, including claims about pet health. Links to sources and other sites leave Pet Human Years. Those sites have their own content and policies.

The site can be wrong, and it can change

We try to keep the math consistent, and the same engine feeds the calculator, the charts, and the share pages. Even so, a formula, a label, a breed weight, or a lifespan range can be outdated or mistaken. Pages can be updated or removed, and the site can be unavailable. Do not rely on a saved number as a permanent record.

You use the site at your own risk. To the extent the law allows, Pet Human Years is not liable for any loss or decision that comes from using these estimates, or from being unable to use the site.

This page is part of the site. It explains the limits of the estimates. It is not legal advice. How we handle visits and analytics is on the privacy policy.