Cat weight calculator: ideal weight by body condition
Enter your cat's weight and body condition score to estimate its ideal weight. On AAHA's table, a cat scoring 6 out of 9 is 10% overweight, 7 is 20%, 8 is 30% and 9 is 40%.
Enter your cat’s weight and pick its score to see an estimated ideal weight.
An estimate from AAHA’s table, not a diagnosis. Set a target weight with your vet before changing what your cat eats.
Ideal weight by body condition score
Source: 2021 AAHA Nutrition and Weight Management Guidelines
Estimated ideal weight for three cats at each score from 5 to 9, worked out by this calculator from AAHA’s table.
| Score | Over ideal | 5 kg (11.0 lb) cat | 6 kg (13.2 lb) cat | 7 kg (15.4 lb) cat |
|---|---|---|---|---|
| 5/9 | ideal | 5.0 | 6.0 | 7.0 |
| 6/9 | 10% | 4.5 | 5.5 | 6.4 |
| 7/9 | 20% | 4.2 | 5.0 | 5.8 |
| 8/9 | 30% | 3.8 | 4.6 | 5.4 |
| 9/9 | 40% | ≤ 3.6 | ≤ 4.3 | ≤ 5.0 |
Scores 1–4: no estimate. At 9, the result is an upper limit.
How much should my cat weigh?
Its own ideal weight, which the scale alone cannot show. Weigh your cat, then score its body condition. A cat that scores 5 out of 9 on WSAVA's chart is at its ideal weight today.
How do I know if my cat is overweight?
Score its body condition by the ribs, the waist and the belly. On WSAVA's chart any score from 6 to 9 is over ideal, and Cornell describes obesity as 20% or more above normal weight.
Not sure of the score? Match your cat against the nine descriptions on the body condition score chart.
How is the ideal weight worked out?
AAHA's 2021 guidelines give a percentage over ideal weight for each score above ideal. The calculator works backwards from today's weight: a cat 20% over its ideal weighs its ideal weight plus a further 20% of it.
What if my cat scores 9?
Treat the result as an upper limit. The scale stops at 9, AAHA lists more than 40% over for cats beyond it, and says a body condition score is limited in cats above 45% body fat.
Is a score of 6 always a problem?
Not always. WSAVA's chart notes that 6 out of 9 may be acceptable in some cats, especially older cats. Ask your vet before starting a diet for a cat that scores 6.
Why is there no estimate for a thin cat?
No source here gives a percentage for scores below 5. AAHA's table starts its percentages at 6 and lists 4 as ideal, while WSAVA's chart puts 4 under ideal. AAHA says a score below 4 needs a fuller check.
Ask your vet how much weight your cat should gain.
How fast should an overweight cat lose weight?
Slowly. Cornell suggests aiming for one or two percent of body weight a week, and warns that a cat put on a sudden starvation diet risks a serious health problem such as hepatic lipidosis.
Plan the diet with your vet, and work out calories for the ideal weight, not today's weight.
Related tools
Sources
How we choose them- WSAVA — Cats: Body Condition Score chart (PDF, 2025)
“IDEAL... 5 Well-proportioned. Ribs felt with slight fat covering. Waist seen behind ribs, but not pronounced... A body condition score of 6/9 may be acceptable in some cats, especially older cats.”
- 2021 AAHA Nutrition and Weight Management Guidelines — Table 2, body condition score and body weight (PDF)
“6 3.5 25–29 10% 7 4 30–34 20% 8 4.5 35–39 30% 9 5 40–45+ 40% >9 >5 — >40%”
- 2021 AAHA Nutrition and Weight Management Guidelines — body condition score (PDF)
“A BCS is limited in its assessment of patients with a high BF% (>45%)... A BCS <4/9 or >5/9, MCS with any degree of loss, and unexplained weight change from the pet’s previous assessment should prompt an extended assessment”
- Cornell Feline Health Center — Obesity
“Feline obesity—generally viewed as body weight that is 20 percent or more above normal weight... What you want to aim for is a gradual weight loss, perhaps one or two percent loss of body weight per week.”