How to Calculate Cat BMI
What is Cat BMI?
Cat body condition scoring (BCS) uses a 1–9 scale to assess whether a cat is at a healthy weight. ~50% of pet cats in developed countries are overweight.
Formula
Cat BMI = Weight (kg) / (Length (m)^2); Ideal 4.0–6.0 kg/m^2; Overweight > 6.5, Obese > 8.5
- Weight
- Cat body weight (kg)
- Length
- Cat body length (Meters (nose to tail base))
Step-by-Step Guide
- 1Score 1–3: Underweight (ribs and spine prominent)
- 2Score 4–5: Ideal (ribs palpable; visible waist)
- 3Score 6–7: Overweight (ribs hard to feel)
- 4Score 8–9: Obese (cannot feel ribs)
Worked Examples
Input
Ribs palpable, slight waist visible from above
Result
BCS 4–5 — Ideal body condition
Frequently Asked Questions
What's ideal cat weight?
Depends on breed. Average domestic: 4–5 kg. You should feel ribs without pressing hard. Spine palpable but not prominent. Slight waist visible from above.
How do I measure cat length?
Nose to tail base (where tail joins spine). Not including tail. Use flexible ruler. For BMI, meter measurement more accurate than visual estimate.
What's obesity risk in cats?
Diabetes 7x higher in obese cats. Arthritis, urinary issues, reduced lifespan. Indoor cats overeat + low activity = overweight common. Diet + activity critical prevention.
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