CritterCalc is a free set of pet care calculators for dog and cat owners. We take the formulas vets and pet nutritionists use and turn them into simple tools that give you a clear answer in seconds. How much should you feed? How big will your puppy get? When are the puppies due? Is the snack your dog just stole dangerous?
Why we built it
Most pet questions come back with “it depends.” Bag feeding charts are written for an average animal, and a lot of advice online skips the math entirely. We wanted tools that use your pet’s actual details and then show their working, so you can see exactly how we got the answer.
How our calculators work
- Published formulas. The feeding tools use the Resting Energy Requirement (RER = 70 × body weight in kg0.75) and standard life-stage factors from veterinary nutrition. The chocolate tool uses theobromine and caffeine levels and dose thresholds published in the Merck Veterinary Manual. The pregnancy tool follows standard canine gestation guidelines. The cat weight tool uses the 9-point body condition score that vets use.
- Results you can check. Most tools include a “How this was calculated” section that lists every step.
- Private by design. Calculations run in your browser. There’s no account to create, and the numbers you type into a calculator aren’t sent to us.
- Kept up to date. When we find better data or someone reports a problem, we fix the tool and its guide.
What we don’t do
CritterCalc isn’t a veterinary service. Our tools give estimates for healthy pets and general information, nothing more. They can’t diagnose illness or recommend medicines, and they don’t replace an exam by your vet.
If your pet seems unwell or you’re worried, contact your veterinarian.
Get in touch
Found a mistake? Want a calculator we don’t have yet? Send us a note through our contact page.