Free Pet Calculators for Dogs & Cats
Convert your pet's age to human years, work out daily food portions, predict your puppy's adult weight, and check life expectancy — all with calculators built on veterinary formulas.
All Pet Calculators
Nine tools covering age, weight, food and health — pick your pet
Dog Calculators
Age, food portions, lifespan, healthy weight and pregnancy.
Dog Age Calculator
Convert your dog's age to human years instantly.
Dog Food Calculator
Calculate daily calories and food amount for your dog.
How Long Do Dogs Live?
Estimate your dog's life expectancy by size and age.
Dog Ideal Weight Calculator
Find your dog's healthy target weight and weight loss plan.
Dog Pregnancy Calculator
Track your dog's pregnancy and due date week by week.
Cat Calculators
Cat age in human years and daily calorie needs.
Puppy Calculators
Adult weight prediction and vaccination timing.
What Is a Pet Calculator?
A pet calculator takes the few things you already know about your dog or cat — their age, weight, and breed size — and turns them into an answer you can actually act on. How old is my cat in human years? How many cups of food does my dog need today? How big will this puppy get? Those questions have real formulas behind them, and that is what these tools run.
Most pet owners rely on rules of thumb that turn out to be wrong. The famous “one dog year equals seven human years” rule is the clearest example — it ignores the fact that dogs do most of their ageing in the first two years, and that a Great Dane ages far faster than a Chihuahua. Feeding is the same story: the guidance printed on a food bag is a broad average, not a portion for your specific pet.
Every calculator on this site uses the published veterinary formula for its job — the AVMA-aligned ageing curve, the Resting Energy Requirement equation for food, and standard growth multipliers for puppies. Nothing is stored, nothing is sent to a server, and you never need an account. Enter a number, get an answer.
Vet formulas
RER, ageing curves and growth multipliers — not guesses.
Instant results
Everything runs in your browser. No waiting, no accounts.
Private by design
Your pet's details never leave your device.
Quick Age Charts
The two questions we get asked most — answered at a glance
Dog Years to Human Years
| Dog's Age | Small (<20 lb) | Medium (20–50 lb) | Large (>50 lb) |
|---|---|---|---|
| 1 year | 15 | 15 | 14 |
| 2 years | 24 | 24 | 22 |
| 5 years | 36 | 37 | 40 |
| 8 years | 48 | 51 | 58 |
| 10 years | 56 | 60 | 72 |
| 14 years | 72 | 78 | 96 |
Human-year equivalents. For your dog's exact number, use the dog age calculator or read the full chart by breed.
Cat Age Chart in Human Years
| Cat's Age | Human Age | Life Stage |
|---|---|---|
| 6 months | 10 years | Kitten |
| 1 year | 15 years | Junior |
| 2 years | 24 years | Young adult |
| 5 years | 36 years | Adult |
| 10 years | 56 years | Mature |
| 15 years | 76 years | Senior |
| 20 years | 96 years | Super-senior |
Try the cat age calculator for months and part-years, or see the complete cat age chart.
The Formulas Behind the Numbers
Nothing here is invented. Each calculator applies a formula that veterinary practices already use — the same equations a vet would reach for when working out your dog's portion size or your cat's life stage. Here are the three that do most of the work.
Daily calories (dogs & cats)
RER = 70 × (body weight in kg)0.75
The Resting Energy Requirement is then multiplied by an activity factor — about 1.0–1.2 for a neutered indoor cat, 1.6 for an active dog, and up to 2.5 for a growing puppy.
Dog age in human years
The first year counts as roughly 15 human years and the second adds about 9 more. After that, each dog year adds 4–7 human years depending on breed size — larger dogs age faster, which is why a 10-year-old Great Dane is older in human terms than a 10-year-old terrier.
Puppy adult weight
Adult weight ≈ (current weight ÷ age in weeks) × 52
Adjusted for breed size, because small breeds finish growing at 9–12 months while giant breeds keep going until 18–24 months.
Popular Guides
The articles pet parents read most
Cat Years to Human Years Chart
Every age converted, kitten to 25
Why the 7-Year Dog Rule Is Wrong
The modern science-based formula
How Much Should I Feed My Dog?
Daily portions by weight and age
How Long Do Indoor Cats Live?
Lifespan and 8 ways to add years
Puppy Growth Chart by Breed Size
Weight expectations month by month
Dog Breeds That Live the Longest
Top 25 long-lived breeds
Frequently Asked Questions
What is a pet calculator?
A pet calculator is a free online tool that turns basic details about your pet — age, weight, breed size, or activity level — into a useful number, such as their age in human years, how many calories they need each day, or how much an adult puppy will weigh. PetCalc's calculators use the same formulas veterinarians rely on, so the results are realistic rather than rough guesses.
Are these pet calculators free?
Yes. Every calculator on PetCalc is completely free, with no signup, no account, and no limit on how many times you use them. They run entirely in your browser, so nothing you enter is stored or sent anywhere.
How accurate is a dog age calculator?
Modern dog age calculators are far more accurate than the old '1 dog year = 7 human years' rule. Dogs age very quickly in their first two years, then slow down, and larger breeds age faster than smaller ones. Our calculator adjusts for both age curve and breed size, which puts the estimate within a year or two for most healthy dogs.
How do I calculate my cat's age in human years?
The standard veterinary approach counts a cat's first year as about 15 human years and the second year as about 9 more, reaching 24 by age two. After that, add roughly 4 human years for every additional cat year. So a 10-year-old cat is around 56 in human terms. Our cat age calculator does this automatically, including part-years for kittens.
How many calories does my pet need per day?
Vets start with the Resting Energy Requirement: RER = 70 x (body weight in kg)^0.75. That number is then multiplied by an activity factor — around 1.0 to 1.2 for a neutered indoor cat, 1.6 for an active adult dog, and up to 2.5 for a growing puppy or kitten. Our dog and cat food calculators apply both steps and convert the result into cups or cans.
Can I predict how big my puppy will get?
Yes, and it is reasonably reliable. The most common method takes your puppy's current weight, divides it by their age in weeks, and multiplies by 52, then adjusts for breed size category. Small breeds finish growing around 9 to 12 months, while giant breeds keep growing until 18 to 24 months. Our puppy weight predictor handles these differences for you.
Do I still need a vet if I use these calculators?
Absolutely. These tools give general estimates for healthy pets and are meant for everyday planning — portion sizes, life stage awareness, growth expectations. They are not a diagnosis. Any sudden weight change, appetite loss, or health concern should go to a licensed veterinarian.
Do the calculators work for mixed breeds?
Yes. For mixed breeds, pick the size category that matches your pet's expected adult weight rather than a specific breed. If you are unsure, use the middle option — mixed-breed dogs often age slightly more slowly than purebreds of the same size, so a mid-range estimate is usually closest.
From the Blog
Pet care guides backed by veterinary research
Puppy Growth Chart: Weight by Age & Breed Size (2026)
How much should your puppy weigh? Use our puppy growth chart by breed size, see when puppies stop growing, and predict adult weight with simple formulas.
How Much Should I Feed My Cat? Daily Cat Feeding Guide
Exactly how much to feed your cat per day — by weight, age, and wet vs dry food. Includes a daily calorie chart, portion sizes, and feeding frequency tips.
Cat Years to Human Years Chart: Every Age Converted (2026)
Exactly how old is your cat in human years? Use our complete cat age chart — from kitten months to 25 years — plus the vet formula and life stages. 1 cat year is not 7.