About Good Pet Day
Small, free calculators for the everyday questions of living with a dog or cat.
What it is
Good Pet Day answers the questions pet owners look up all the time: how old is my dog in human years, how much should my cat eat, how big will this puppy get, is that food safe, and what does the sitter need to know. Each calculator shows its working and names the published source behind every formula and threshold, such as the AVMA, AAHA and AAFP guidelines, the Merck Veterinary Manual, WSAVA and the ASPCA.
How it works
Everything runs in your browser. The formulas and food lists are part of the page, so nothing you type is sent anywhere, and once a page has loaded it keeps working without a connection. The care sheet and name favourites are kept in your browser's local storage on your device and nowhere else. There are no accounts, cookies or ads.
What it is not
It is not veterinary advice. Published formulas describe typical pets; yours is an individual. Where the science is uncertain the calculators give ranges, and they leave out anything we could not trace to a trustworthy source. Medication doses and treatments are deliberately not covered: those belong to your vet. If your pet is unwell or has eaten something harmful, call your vet or an animal poison control line straight away.
Check our working
Every calculator page ends with its sources, linked where they are online, so you can check each number against the original.