Free Pet Health Calculators for Dogs and Cats
27 free calculators for dog and cat owners, built and checked by Dr Duncan Houston, an Australian emergency veterinarian. No account, no email, no cost.
Chocolate and xylitol toxicity, daily calories and feeding amounts, ideal weight and body condition, water intake, pain and quality of life scoring, vaccination and worming schedules, parasite treatment, and what a pet really costs. Every tool shows the number it used to reach its answer.
Quick answer
Search below or filter by category. If your pet has eaten something toxic, start with the poison calculators in the red box. If you are a vet or nurse after clinical dosing tools, use the veterinary calculators for vets and nurses instead.
Emergency: my pet ate something
If your pet is collapsed, struggling to breathe, having a seizure, bloated and unproductively retching, or bleeding heavily, stop reading and call your nearest emergency veterinary hospital now. These tools do not replace that call.
Jump back in
All 27 free pet tools, A to Z
Antihistamine Dose Calculator
Weight-based doses of single-ingredient antihistamines for dogs and cats, and why most allergy packets on the shelf must never be given.
Chocolate Toxicity Calculator
Theobromine dose from the chocolate type, the amount eaten and your dog's weight. Signs start near 20 mg/kg and seizures near 60 mg/kg.
Daily Calorie Calculator
How many calories your dog or cat actually needs each day, from resting energy requirement adjusted for age, desexing and activity.
Emergency Symptom Checker
Answer a short set of questions and find out whether your pet needs a vet right now, later today, or can safely wait until morning.
General Toxins Calculator
Grapes, lilies, rat bait, snail bait, medications and dozens more common household poisons, checked against your pet's body weight.
Homemade Dog & Cat Food Calculator
Estimate the energy, protein and calcium a home-cooked diet needs to hit, and see where the recipes circulating online fall short.
Human Years Calculator
A realistic dog and cat age conversion based on size and species, rather than the multiply-by-seven myth that has never been true.
Ibuprofen & Paracetamol Toxicity Calculator
Human painkillers are one of the most common serious pet poisonings, and cats have no safe dose of paracetamol at all. Check what was swallowed.
Ideal Weight Calculator
Your pet's target weight from breed, frame and body condition, and how many kilos need to come off to get there safely.
Onion & Garlic Toxicity Calculator
Allium doses that matter, including the cooked and powdered forms owners miss. Cats are affected at far smaller amounts than dogs.
Pain Scale Calculator
Pets hide pain well. Score the behavioural signs vets grade in consult and find out whether yours is sore enough to need treating.
Parasite Treatment Finder
Give it your pet's species, age and what you need covered, including paralysis tick, and it finds the one product or minimal combination that does it.
Perfect Pet Picker
Match your home, hours, budget and experience to the species and breeds that will actually suit you, from a vet who sees the mismatches.
Pet Anaesthetic Risk Estimator
Understand your pet's anaesthetic risk before surgery or a dental, and the questions worth asking your own vet beforehand.
Pet BMI & Body Condition Calculator
Score your pet on the 9-point body condition chart vets use. Five out of nine is ideal, and each point above is roughly 10 percent overweight.
Pet Food Shopping List & Meal Prep Calculator
Turn a daily feeding amount into how much food to buy, how long a bag lasts and what your pet actually costs to feed each month.
Pet Food Transition Calculator
A day-by-day mixing schedule for switching your pet onto a new food without triggering diarrhoea.
Pet Insurance Comparison Calculator
Compare policies on what actually decides a claim: excess, annual limits, per-condition sub-limits and whether cover is genuinely lifetime.
Pet Supplement Dose Calculator
Doses and honest evidence ratings for 85 supplements, from fish oil and glucosamine through to the ones not worth your money.
Pregnancy & Due Date Calculator
Work out gestation stage, the whelping or queening date and what to prepare when, from the mating dates you have.
Puppy & Kitten Feeding Calculator
Growth-stage feeding amounts for puppies and kittens that change as they grow, instead of one fixed number on the back of a bag.
Quality of Life Calculator
A structured, honest score for pain, mobility, appetite and joy in an ageing or unwell pet, for when you need something other than a gut feeling.
True Cost of Owning a Pet Calculator
Lifetime cost of a pet including food, prevention, insurance, grooming and the emergency vet bills nobody budgets for.
Vaccination & Parasite Schedule Builder
A one-page printable vaccination and worming schedule for a single pet, for the fridge door or the clinic wall.
Vaccination, Worming & Flea Calendar
Build a full first-year and lifelong C3, C5 and F3 prevention schedule from your pet's date of birth, then sync every due date to your phone.
Water Intake Calculator
Normal is roughly 50 to 60 mL per kilo a day. Above about 100 mL/kg is polydipsia, and that is a kidney and diabetes conversation.
Xylitol Toxicity Calculator
About 0.1 g/kg can crash a dog's blood sugar and 0.5 g/kg risks liver injury. Covers gum, mints, peanut butter and baking.
Are you a vet, nurse or student?
The clinical side lives on its own page: anaesthetic drug calculators, CRI, IV fluid rates, blood gas, electrolyte corrections, triage and staging scores. Free, no login.
These tools answer one question. The app remembers the answers.
Weights, vaccinations, worming, medications, symptoms, photos and vet notes for every pet in your household, in one place. Plus certified vet chat when a calculator is not enough.
What these pet calculators do
Most pet questions do not need an appointment. They need a number, a threshold and a straight answer about whether to worry. That is what these tools are. Each one takes the reasoning a vet uses in consult and turns it into something you can run in thirty seconds at home, at 11pm, with the dog looking guilty beside an empty wrapper.
They are free, there is no sign-up, and nothing you type leaves your browser. Every tool is written and reviewed by a practising emergency and general practice veterinarian, and each one shows its working, so you can see how it reached the answer instead of being asked to trust a black box.
How to use these calculators
Search the worry, not the tool name
Type what is actually happening. “Chocolate”, “drinking a lot” or “how much food” will find the right calculator faster than scrolling will.
Use a real weight in kilograms
Almost every calculation starts with body weight, and a guess that is 20 percent out makes the answer 20 percent out. Weigh at the vet, or weigh yourself holding your pet and subtract.
Read the working, then the advice
Each tool shows the figure it applied and what to do next. If the result and your gut disagree, trust your gut and call a vet.
The numbers these calculators use
Most calculator sites hide the maths inside a widget. These are the published figures the tools apply, written out so you can check them, quote them to your vet, or work the answer out yourself.
How much chocolate is toxic to a dog?
Signs typically start around 20 mg/kg of theobromine, cardiac effects appear around 40 to 50 mg/kg, and seizures become likely at 60 mg/kg and above. Because dark and cooking chocolate carry many times the theobromine of milk chocolate per gram, the type matters more than the amount. A 10 kg dog can eat a surprising volume of milk chocolate and be fine, while a much smaller amount of 70 percent dark is a genuine emergency. Run the numbers for your dog.
How much xylitol is dangerous to a dog?
Around 0.1 g/kg can drop a dog's blood glucose, and around 0.5 g/kg and above carries a risk of liver injury. Sugar-free gum is the usual culprit and a few pieces can be enough for a small dog. Xylitol also turns up in mints, some peanut butters, baking products and toothpaste. Cats appear far less sensitive, but the dose still matters. Check the amount eaten.
How much onion or garlic is toxic to a dog or cat?
Onion toxicosis is reported from roughly 15 to 30 g/kg in dogs and from around 5 g/kg in cats, with garlic substantially more potent by weight. Cooking does not remove the risk, and the powdered forms in stock cubes, gravies and baby food are easy to overlook because the volume looks small. Work out the dose.
How many calories does my dog or cat need a day?
Start with resting energy requirement: 70 multiplied by body weight in kilograms to the power of 0.75, which gives kilocalories per day. That figure is then multiplied by a life-stage and activity factor. A desexed adult dog at maintenance sits near 1.6 times RER, an entire working dog considerably higher, and a weight-loss plan lower. Guidance printed on a food bag is a population average, not a prescription for your animal. Get the figure for your pet.
How much water should a dog or cat drink a day?
Roughly 50 to 60 mL per kilogram of body weight per day is normal. Sustained intake above about 100 mL/kg/day is polydipsia and warrants kidney, diabetes and thyroid testing. Increased drinking is one of the earliest visible signs of several serious diseases, and it is the sign owners most often dismiss as the pet just being thirsty. Measure it properly.
What body condition score should my pet be?
Five out of nine on the WSAVA body condition chart. Each point above ideal is roughly 10 percent over target weight, so a dog at 7 out of 9 is about 20 percent overweight. Body condition score is the measure vets actually use; there is no accepted canine body mass index, because a species spanning a chihuahua to a mastiff cannot share one height-and-weight formula. Score your pet.
Can I give my dog paracetamol or ibuprofen?
No, not on your own initiative. Cats cannot safely metabolise paracetamol and a single tablet can kill one; ibuprofen has no safe household dose in either species and causes stomach ulceration and kidney injury. Dogs are occasionally prescribed paracetamol by a vet at a controlled dose for a specific reason, which is not the same as it being safe to reach for. If your pet is sore, the honest answer is a vet visit and a drug licensed for their species. If they have already swallowed some, check the dose.
How do I know if my dog or cat is in pain?
Look for changes rather than complaints. Reluctance to jump, slowness on stairs, a hunched or tucked posture, licking one spot, sleeping in a new place, going off food, flinching when touched, or a normally social animal withdrawing. Cats in particular hide pain almost completely; a cat that has simply gone quiet is a cat worth examining. Limping is the obvious sign and the least common one. Score the signs properly.
When do puppies and kittens need their vaccinations?
The first vaccination is usually given at 6 to 8 weeks, then repeated every 2 to 4 weeks until at least 16 weeks of age, with a booster around 12 months. The last dose of the puppy or kitten course matters more than the number of doses, because maternal antibody can block an early vaccine without anyone knowing. In Australia you will see this written as C3 or C5 for dogs and F3 for cats. Build the full schedule from your pet's date of birth.
Are pet calculators accurate?
A calculator is exactly as accurate as the number you put into it and the assumption built into it. These ones are accurate about arithmetic and honest about the rest. Where a threshold is a range in the literature, the tool says so rather than inventing a single figure. Where the evidence is weak, it says that too.
What they cannot do is examine your pet. A dose can sit under a toxic threshold and still be a problem in an animal with kidney disease, a heart murmur or an empty stomach. Treat every result as the start of a decision rather than the end of one. If a tool tells you to call a vet, that is the answer, not a disclaimer.
Are these calculators right for Australian pets?
They are built here, so yes. Weights are in kilograms with an imperial toggle where it matters. Vaccination schedules use the Australian C3, C5 and F3 vocabulary rather than the American equivalents. The parasite tools model paralysis tick, which does not exist in most of the world and which overseas calculators simply do not account for. Product names in the parasite finder are the ones actually registered and sold here.
If you are outside Australia the arithmetic still holds, but check product names, vaccine schedules and poison helpline numbers against your own country before acting.
Terms you will see in these tools
- mg/kg
- Milligrams of a substance per kilogram of body weight. Almost every toxicity threshold is expressed this way, which is why the same biscuit is trivial for a labrador and serious for a chihuahua.
- Body condition score (BCS)
- A 9-point visual and hands-on scale vets use to judge body fat. Five is ideal; each point above is roughly 10 percent over target weight.
- Resting energy requirement (RER)
- The calories an animal burns doing nothing. Every feeding calculation starts here and is then multiplied by a life-stage factor.
- Theobromine
- The stimulant in cocoa that dogs clear far more slowly than people do. It, not the sugar or fat, is what makes chocolate dangerous.
- Polydipsia
- Drinking more than normal, defined as sustained intake above roughly 100 mL per kilogram per day. One of the earliest signs of kidney disease and diabetes.
- C3, C5 and F3
- Australian shorthand for core vaccine combinations. C3 covers distemper, hepatitis and parvovirus in dogs, C5 adds kennel cough, and F3 covers the core feline viruses.
- Paralysis tick
- Ixodes holocyclus, found along the Australian east coast. It causes ascending paralysis and is the reason Australian parasite prevention differs from advice written overseas.
Who built these tools
Dr Duncan Houston is a veterinarian who graduated from the University of Sydney and has worked in emergency and general practice in Australia and Hong Kong. Every tool here was written, built and reviewed by him rather than assembled from scraped content, which is more than most pet calculator sites can say.
Tools are revisited when guidelines change. If you find something wrong, tell me and it gets fixed.
Pet calculator FAQ
Are these pet calculators free?
Yes. Every tool on this page is free, with no account, no email and no trial. They are built by ASK A VET™ as genuinely useful resources for pet owners.
Are pet calculators accurate?
They are accurate about the arithmetic, and only as good as the weight and detail you put in. Every threshold used is a published population figure, and each tool shows the number it applied. What no calculator can do is examine your pet, so a result that sits under a toxic threshold can still matter in an animal with other health problems.
How much chocolate is toxic to a dog?
Theobromine is the problem, and it is dose-dependent on body weight. Signs typically begin around 20 mg/kg, cardiac effects around 40 to 50 mg/kg, and seizures at 60 mg/kg and above. Because dark and cooking chocolate carry many times the theobromine of milk chocolate, the type matters more than the amount. The chocolate calculator does the conversion for you.
Who wrote and checked these tools?
Dr Duncan Houston, a veterinarian who graduated from the University of Sydney and works in both emergency and general practice. Each tool is built from published veterinary dosing and guideline data, and is reviewed and updated as guidelines change.
Can I use these instead of seeing a vet?
No. They are decision-support tools, not a diagnosis. They help you work out how urgent something is and what to tell your vet, not replace an examination. If your pet is unwell, see a vet.
What weight should I enter, and in what units?
Current body weight in kilograms, measured rather than estimated, because owners routinely guess low. Weigh your pet on the walk-in scales at your vet clinic, or stand on your bathroom scales holding them and subtract your own weight. Tools that need an imperial figure have a pounds toggle.
Do the tools work for cats as well as dogs?
Most do, and each tool states which species it covers. Cats are not small dogs, so where a species difference matters clinically the tool handles them separately rather than scaling a dog figure down.
Are these calculators right for Australian pets?
Yes. They use kilograms, Australian vaccine terminology such as C3, C5 and F3, and products registered for sale in Australia, and the parasite tools account for paralysis tick. Outside Australia the arithmetic still holds but you should check product names, vaccination schedules and helpline numbers locally.
My pet is not a dog or cat. Can I still use these?
A few can help. The Parasite Treatment Finder covers rabbits and ferrets, and the Pregnancy and Water Intake calculators cover a wider range of species. Everything else is written for dogs and cats only, and applying a dog calculation to a rabbit, bird or reptile is not safe. For exotics, speak to a vet who sees them regularly.
Do you store what I type into the calculators?
No. The tools run entirely in your browser. Nothing you enter is sent to a server or stored by ASK A VET™, and the only thing saved on your device is a short list of which tools you opened, so this page can show them again.
Where are the clinical calculators for vets and nurses?
On the clinical calculators page. Those are written for veterinary professionals and assume clinical training, so they are kept separate from the owner tools.