Cat BMI Calculator

Estimate a cat's body mass index from weight and length and translate it into a body-condition category.

837.9K uses Updated · 2026-05-12 Runs locally · zero upload
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How to Use Cat BMI Calculator

The Cat BMI Calculator helps you screen for under/overweight using two measurements at home.

  1. Weigh on a flat scale — Hold the cat and subtract your own weight, or use a digital pet scale.
  2. Measure body length — Tape from the tip of the nose to the base of the tail with the cat standing.
  3. Optionally add chest girth — Useful for cats with unusual builds like sphynx or Bengals.
  4. Read the category — Pair the result with a body-condition score chart from your vet.

Formula & Theory — Cat BMI Calculator

A cat-adapted BMI normalises weight by length squared:

BMI = weight_kg ÷ (length_m)²
# under: < 8
# healthy: 8-16
# over: 16-25
# obese: > 25

Use Cases for Cat BMI Calculator

Setting a weight-loss target, tracking growth in adolescents, monitoring senior cats with sarcopenia, or screening shelter cats.

The Cat BMI Calculator is a quick reference, not a substitute for veterinary advice. Always cross-check with a vet, especially for medication or toxicity questions.

Frequently asked questions about Cat BMI Calculator

Why is BMI less reliable in cats?

Cats have proportionally longer torsos and looser belly skin than dogs or humans. Combine BMI with body-condition palpation.

How quickly should an overweight cat lose?

No more than 1–2% of body weight per week. Faster loss risks hepatic lipidosis (fatty liver).

Should I use weight or BMI for vet visits?

Weight + BCS together are the gold standard. BMI is a useful home tracker between visits.

Does breed affect BMI ranges?

Yes — Maine Coons and Norwegian Forest cats are naturally larger; ranges should be interpreted with breed in mind.

Is my data stored?

No. All calculations happen in your browser; nothing is sent to a server.