Cat weight calculator
Is your cat a healthy weight? Estimate the ideal weight from body condition and breed, see how far off you are, and get the calories and a safe timeline to get there — free, no sign-up.
Common questions
How do I know my cat's ideal weight?
Body condition matters more than the scale. Feel the ribs and look for a waist, score it 1–9, and the tool estimates the ideal weight from there — cross-checked against the healthy range for the breed.
What is a body condition score?
A 1–9 scale vets use: 5 is ideal, below 5 is too thin, above 5 is overweight. Each point above ideal is roughly 10% over the ideal weight.
How fast can a cat safely lose weight?
Cats must lose weight very slowly — around 0.5–1% of body weight per week. Faster loss can trigger a dangerous liver condition (hepatic lipidosis), so always plan a cat's diet with your vet.
Where do the calories come from?
From the resting energy requirement, RER = 70 × (ideal weight in kg)^0.75 — the standard formula — times a life-stage factor. To slim down we target the calories for the ideal weight, which creates a gentle deficit.
Is this a substitute for the vet?
No. It's a helpful estimate to start the conversation, not a diagnosis. A sudden weight change, or any weight-loss plan, is always worth a vet's eye.