Cat BMI Calculator

Your details

Measure around the widest part of the rib cage, just behind the front legs, at the level of the 9th rib. Cat should be standing with its head upright.
cm
Measure the hind leg from the knee (stifle joint) to the ankle (hock). Keep the tape parallel to the bone.
cm
Sex is used only for the contextual note - it does not alter the FBMI formula.
Spayed and neutered cats have a 20-30% lower calorie need, making weight gain more likely. This context appears in the insight panel.
FBMI thresholds apply to adult cats. For kittens, measurements change rapidly; veterinary assessment is recommended.
Feline BMI (FBMI)Normal weight
25.9

Feline Body Mass Index based on body proportions

Weight categoryNormal weight
Rib cage needed for low-normal FBMI25.9
Rib cage for ideal FBMI (22)30.5
Rib cage needed for high-normal FBMI35.6
Measurement tipYour cat is in the normal FBMI range.
25.9 FBMI
Underweight<15Normal15-30Overweight30-42Obese42+

Your cat's FBMI is 25.9, in the normal weight range.

  • An FBMI of 15-29.9 is the normal range. The cat's ribs should be easy to feel but not prominent, and a gentle waist should be visible from above.

Next stepKeep up the good work. Recheck the FBMI every 3-6 months and adjust portions seasonally (indoor cats often move less in winter).

 = Powered by OnlyCalculators