Pet BMI Calculator

Calculate your pet's Body Mass Index to determine if they are at a healthy weight. Works for dogs and cats.

Results

Visualization

How It Works

Unlike humans, there is no single universal BMI formula for pets because breed variation is enormous (a Chihuahua and a Great Dane are the same species). Veterinarians typically use the Body Condition Score (1-9 scale) combined with body measurements. The girth-to-length ratio is a practical at-home measurement: measure around the widest part of the rib cage and divide by the length from chest to rump. For dogs, a ratio above 1.2-1.3 suggests excess weight. For cats, above 1.1-1.2. Pet obesity is epidemic: 56% of dogs and 60% of cats in the US are overweight or obese, leading to diabetes, joint disease, reduced lifespan, and lower quality of life.