Estimate a rough body-mass index band for a dog or cat from weight and body length.
| BMI | – |
| Band | – |
Use this calculator to obtain a coarse underweight / OK / overweight / obese band from body weight and length. Select the species, then enter current weight and body length measured from the nose to the base of the tail, with the animal standing naturally. This is not a hands-on body condition score and not veterinary advice. Length is not height at the withers.
The calculation is: BMI = weight ÷ (length)², with weight in kilograms and length in metres. You can enter weight in kilograms (kg) or pounds (lb), and length in centimetres (cm) or inches (in); the calculator converts both before the formula. Dog bands: below 20 underweight, 20–30 OK, 30–35 overweight, 35 and above obese. Cat bands: below 15 underweight, 15–30 OK, 30–42 overweight, 42 and above obese.
Breed, muscle, coat, and pregnancy change how BMI maps to condition. Treat the result as a conversation aid, not a diagnosis.
Species: Dog or cat; the band thresholds differ.
Weight: Current body weight, in kg or lb.
Body length: Nose to the base of the tail, in cm or in.
BMI: Body-mass index in kg/m².
Band: Coarse condition band for the selected species.
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