17 free calculators built on veterinary sources
Pet math, done properly.
Quick, careful answers to the questions pet owners actually ask, from how much to feed each day to whether that missing chocolate bar needs a trip to the vet. Every tool shows its working and where the numbers come from.
Formulas and charts from published guidance by
- Merck Veterinary Manual
- AAHA
- ASPCA
- Pet Nutrition Alliance
- AAFP
Start with your pet
Pick an animal to see every calculator for it, grouped by what you want to work out.
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10 calculators
Dogs
Feeding, age, weight, pregnancy, heat cycles, health checks and crate sizing.
Browse dog calculators
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6 calculators
Cats
Wet and dry food portions, calories, healthy weight, cat years and kitten ages.
Browse cat calculators
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1 calculator
Fish
Gallons and liters for rectangular, cube, cylinder and bow front tanks.
Open the tank calculator
Every calculator
All 17 tools, free and ready on your phone. Each one shows a sample of the answer it gives.
Dog calculators
Browse by topic- Feeding Dog food calculator How many cups or grams of your food to feed each day.
- Feeding Dog calorie calculator Daily calories for your dog’s weight, age and lifestyle.
- Feeding Dog weight loss calculator Ideal weight, daily calories and a safe timeline to get there.
- Age and growth Dog age calculator Your dog’s age in human years, adjusted for size.
- Age and growth Puppy weight calculator Estimate how big your puppy will be as an adult.
- Health Chocolate toxicity calculator Check how serious a chocolate snack is for your dog.
- Breeding Dog pregnancy calculator Due date and week-by-week dates from the mating day.
- Breeding Dog heat cycle calculator When the next heat starts and her likely fertile days.
- Health Dog water intake calculator How much water is normal, and when thirst is a warning sign.
- Home Dog crate size calculator The right crate size from two quick measurements.
Cat calculators
Browse by topic- Age and growth Cat age calculator Cat years to human years, with life stages.
- Feeding Cat food calculator How much wet food, dry food or a mix to feed each day.
- Feeding Cat calorie calculator Daily calories for your cat’s weight and lifestyle.
- Feeding Cat weight calculator Is your cat overweight? Ideal weight and a safe diet plan.
- Age and growth Kitten age calculator Estimate a kitten’s age from its weight, plus a weight chart.
- Breeding Cat pregnancy calculator Kittens’ due date and a week-by-week timeline.
Built like a vet reference, as easy as an app
Pet advice online is full of rules of thumb. These tools replace them with the charts and formulas vets use, and show their working.
Sources you can check
Each calculator uses published veterinary references, such as the Merck Veterinary Manual and AAHA guidelines, and links to them at the bottom of the page.
The working, shown
You’ll see the formula or chart behind every result, plus a worked example, so you can sanity-check the number before you rely on it.
Honest about limits
These are estimates. When a result could mean your pet needs care, we say so plainly and tell you who to call.
Private by design
The numbers you type are worked out in your own browser. They aren’t sent to us or stored anywhere, and there’s nothing to sign up for.
The “times seven” rule gets most dogs wrong
Dogs race through their first two years, then age at a pace set by their size. At ten, a Chihuahua is about 56 in human terms and a Great Dane about 78. Drag the slider to see how a medium-sized dog ages.
Try it with your dog’s sizeBased on the AAHA size chart for dogs of 21 to 50 lb.