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Cat weight calculator
Is your cat a healthy weight? Score its body condition to estimate its ideal weight, or take two tape measurements to estimate its body fat.
Your result will show here.
An estimate to discuss with your vet. Last reviewed October 7, 2026.
How much should a cat weigh?
The average adult house cat weighs about 8–12 lb (3.6–5.4 kg), according to PetMD. But a healthy weight depends on the cat's frame: a small-boned cat can be overweight at 10 lb, and a large Maine Coon can be lean at 16 lb. That's why vets judge weight by body condition rather than the number on the scale.
Body condition score for cats
Vets score cats on a 9-point scale where 5 is ideal (many charts count 4–5 as ideal). Run your hands along your cat's sides and look from above and from the side:
| Score | What you feel and see |
|---|---|
| 1–3, underweight | Ribs, spine or hip bones are easy to feel or see, with little or no fat. |
| 4–5, ideal | Ribs can be felt under a slight layer of fat. There is a visible waist behind the ribs and only a small belly fat pad. |
| 6–7, overweight | Ribs are harder to feel. The waist is hard to see and the belly is rounded. |
| 8–9, obese | Ribs can't be felt under heavy fat. No waist, a hanging belly, and fat over the back. |
The 2014 AAHA Weight Management Guidelines say each point above 5 on the 9-point scale equals being about 10% overweight. The calculator uses that rule: a 12 lb cat with a score of 7 is about 20% over, so its ideal weight is about 10 lb. According to the Merck Veterinary Manual, cats 10–20% above ideal weight count as overweight, and more than 20% above as obese.
Feline body mass index (FBMI)
The feline body mass index was developed by Butterwick and Hawthorne at the WALTHAM Centre for Pet Nutrition (2000). It estimates body fat from two measurements:
Body fat % = ((rib cage ÷ 0.7062) − leg) ÷ 0.9156 − leg, with both measurements in cm.
In the published method, 10–30% body fat is considered normal, and 30% or more means the cat is overweight and should be checked by a vet. Measure with a soft tape, with your cat standing, and repeat a couple of times to make sure the numbers are steady.
Helping your cat lose weight
AAHA recommends that cats lose 0.5–2% of their body weight per week. Faster loss is risky: cutting a cat's food too hard can trigger hepatic lipidosis, a serious liver disease. Measure meals by weight, cut treats, and add play. The cat food calculator shows how many calories your cat needs, and your vet can set a target weight and pace.
Questions people ask
How do I know if my cat is overweight?
Feel the ribs. If you can't feel them easily under a thin layer of fat, and your cat has no visible waist when you look from above, it is probably overweight. A body condition score of 6 or more on the 9-point scale means overweight.
What is a healthy weight for a cat?
Most adult house cats weigh about 8–12 lb, but the right weight depends on frame size. A body condition score of 4–5 out of 9 is ideal whatever the scale says.
How fast should an overweight cat lose weight?
Slowly: about 0.5–2% of body weight per week, according to AAHA. For a 15 lb cat that's roughly 1–5 oz a week.
How do I calculate my cat's ideal weight?
Score its body condition. Each point above 5 is about 10% extra weight, so divide the current weight by 1.1 for a score of 6, by 1.2 for 7, by 1.3 for 8 and by 1.4 for 9. The calculator above does this for you.