Cat Ideal Weight Calculator (Body Condition Score)

By Marcos Ortega · Updated October 25, 2026 · Runs in your browser; nothing you type is sent anywhere.

Educational estimate, not veterinary advice. These numbers come from published averages and can be wrong for your pet. Your veterinarian, who can examine your dog or cat, is the right person to decide what is healthy for them.

Cats come in different frames, so a breed or “average cat” weight isn’t much help. The body condition score (BCS) looks at your own cat’s fat cover instead. Combined with today’s weight, it gives a rough idea of what your cat would weigh at an ideal condition.

Step 1: score your cat (1–9)

WSAVA publishes a 9-point body condition chart for cats. In short:

Score	Group	What you see and feel (summary)
1–3	Too thin	Ribs, spine and hip bones easy to see or feel, with little or no fat
4–5	Ideal	Well proportioned; ribs felt with a slight fat covering; waist visible behind the ribs; little belly fat
6–7	Overweight	Ribs felt only under extra fat; waist hard to see; rounded belly with a noticeable fat pad
8–9	Obese	Ribs very hard or impossible to feel; no waist; heavy fat on the belly, back and face or limbs

Our summary. For the official descriptions with drawings, see the WSAVA chart linked in the sources.

Step 2: estimate the ideal weight

AAHA’s 2021 nutrition and weight-management guidelines for dogs and cats relate each score to how far over ideal weight a pet is: 6 = 10%, 7 = 20%, 8 = 30%, 9 = 40% (above 9, more than 40%). Scores of 4 and 5 are ideal.

Ideal weight = current weight ÷ (1 + 0.10 × (BCS − 5))

AAHA also gives a body-fat formula, ideal weight = current weight × (100 − % body fat) ÷ 80, which needs a body-fat estimate from your vet.

Worked examples

Example 1: a 14 lb cat with a BCS of 7. 20% over ideal → 14 ÷ 1.20 = 11.7 lb, about 2.3 lb to lose.

Example 2: a 12 lb cat with a BCS of 6. 10% over → 12 ÷ 1.10 = 10.9 lb.

Example 3: a 9 lb cat with a BCS of 5. Ideal range → 9 lb, no change.

What to do with the result

See your veterinarian before changing your cat’s diet. They will confirm the score, set the target and check for medical causes.
Feed for the target your vet sets. Our cat food calculator shows how calorie needs are estimated.
Re-weigh and re-score regularly, so you can see whether the plan is working.

Limitations

The 10%-per-point rule is an average and less certain at the extremes (a score of 9 may mean more than 40% over).
Long coats make scoring by eye unreliable: always use your hands.
No estimate is given for underweight cats (scores 1–3).

Frequently asked questions

What is a healthy weight for a cat?

It depends on the cat's frame, so there isn't one number. Veterinary guidelines judge it by body condition: on the 9-point scale, 4 and 5 are ideal. This calculator turns that score into a rough target weight for your own cat.

How do I score my cat?

Run your hands along the ribs and look from above and from the side. At an ideal score you can feel the ribs with only a slight fat covering and see a waist behind them. Your vet can score your cat at the next visit, which gives you a reliable reference point.

How quickly should my cat lose weight?

Slowly, and only with a plan from your veterinarian. Weight loss in cats should never be done by sharply cutting food on your own.

Why no estimate for thin cats?

A low score can be caused by illness as well as by underfeeding, so the calculator leaves underweight cats to your vet.

Cat Ideal Weight Calculator (Body Condition Score)