Free Pet Calculators & Tools

Instant answers to the numbers pet owners actually need — no account, no email

Seven free calculators for the numbers that come up when you own an animal: how much to feed a dog or a cat, how much water is really in an aquarium, what wattage heater it needs, how big a puppy will grow, how old a pet is in human years, and how many litter boxes a household should have. Each one runs instantly in the browser, with no account and no email.

What each tool does

Dog food calculator: How many calories and grams your dog actually needs each day.

Cat food calculator: Daily calories for a cat, and why free-feeding goes wrong.

Aquarium volume calculator: Real water volume, filter turnover and water change size.

Heater wattage calculator: What wattage heater your tank needs, and when to use two.

Puppy weight calculator: Estimate the adult weight of a growing puppy.

Pet age calculator: Dog and cat years done properly — not multiplied by seven.

Litter box calculator: How many boxes, how deep, and how much litter a month.

How these tools work

Every calculator uses a published formula and each page names the formula it uses. The feeding calculators use the Resting Energy Requirement equation from veterinary nutrition. The aquarium tools use the volume and turnover arithmetic aquarists have used for decades. The age calculator uses the curve veterinary bodies describe, not the multiply-by-seven myth.

Nothing here is a diagnosis and nothing replaces your vet. Where a result depends on the individual animal — which is most of them — the page says so and tells you what to check instead.

Frequently asked questions

Are these pet calculators free?

Yes. Every tool runs in your browser with no account, no email and no paywall.

How accurate are the results?

They use published formulas and are accurate as estimates. Anything that depends on an individual animal — metabolism, breed, health status — will vary, which is why each page tells you what to measure and adjust against.

Do these replace veterinary advice?

No. They are planning tools. Weight loss, any diagnosed condition, and any change in an animal's behaviour need your vet.

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