⚖️ Cat Weight Calculator
This cat calculator checks whether your adult cat is at a healthy weight, or works as a size predictor to estimate how big your kitten will get. Results are based on breed type and typical feline growth patterns.
Why Cat Weight Varies So Much by Breed
A healthy Siamese and a healthy Maine Coon are both "normal weight" — but they might differ by 10 lbs or more. This is why a single number like "the average cat weighs 10 lbs" is practically useless without breed context.
Breed weight ranges also differ significantly by sex. Male cats of most breeds outweigh females by 2–4 lbs on average. A 12 lb female Maine Coon is likely underweight; a 12 lb male Siamese is significantly overweight. Both calculations start with the same number but lead to very different conclusions.
The Body Condition Score: More Reliable Than the Scale
Vets use a Body Condition Score (BCS) on a 1–9 scale to assess weight, not just a number in pounds — a simpler, hands-on alternative to the formal Feline BMI (FBMI) formula, which requires measuring rib cage circumference and leg length. BCS 4–5 is ideal. Here's a simple at-home assessment:
- Rib check: Run flat hands along your cat's sides. You should feel each rib with light pressure — not see them, but not have to dig for them either.
- Waist check: View from above. Most cats at healthy weight show a slight inward taper behind the ribs. No visible waist often means excess weight.
- Belly tuck: View from the side. The belly should tuck slightly upward between the ribs and hind legs. A sagging belly or prominent belly pouch suggests excess fat.
One important note for senior cats: muscle loss (sarcopenia) is common with age and can mask weight problems. A cat that has lost muscle may look lean or weigh less than before — while still carrying excess fat. The BCS assessment catches this better than scale weight alone.
Typical Healthy Weight Ranges by Breed
| Breed | Female | Male |
|---|---|---|
| Siamese | 6–8 lbs | 8–10 lbs |
| Domestic Shorthair / Mixed | 8–10 lbs | 10–12 lbs |
| Persian | 7–10 lbs | 9–12 lbs |
| British Shorthair | 9–12 lbs | 12–17 lbs |
| Norwegian Forest Cat | 9–12 lbs | 12–16 lbs |
| Ragdoll | 10–15 lbs | 15–20 lbs |
| Maine Coon | 10–14 lbs | 15–25 lbs |
Want to know how much your cat should eat? → Use the Pet Food Calorie Calculator
Want a general age-by-age reference table instead of a personalized prediction? → See the Kitten Weight Chart by Age for typical growth benchmarks, or use "Estimate my kitten's adult size" above for a prediction based on your kitten's own current age and weight.
Weight on the low end? → How to Tell If Your Cat Is Underweight
Extra weight is hard on feline joints. If an older cat has also stopped jumping or using stairs normally → Cat Arthritis Screening Tool
Frequently Asked Questions
How much should a cat weigh?
Most adult domestic cats weigh between 8 and 12 lbs, but the healthy range varies significantly by breed. A healthy Siamese may weigh 6–10 lbs while a healthy Maine Coon can weigh 10–25 lbs. Body condition score is a more reliable indicator of healthy weight than a number on the scale.
How can I tell if my cat is overweight?
Run your fingers along your cat's sides with light pressure. You should feel each rib easily without pressing hard. From above, your cat should have a visible waist — a slight inward curve behind the ribs. If the waist is absent or the belly sags noticeably, your cat may be carrying excess weight.
Is there a BMI for cats?
There is a research formula — the Feline Body Mass Index (FBMI), based on rib cage circumference and lower leg length (Butterwick, 2000) — but it needs a tape measure and some arithmetic, and it is not a human-style BMI. In practice, veterinary teams use a 9-point body condition score, and the rib, waist and belly check above gives a comparably reliable read using just your hands.
How big will my cat get?
Switch to "Estimate my kitten's adult size" above, enter your kitten's current age and weight and choose the expected adult size category. You'll get a predicted adult weight range based on your kitten's own numbers rather than a general table. For age-by-age benchmarks instead, see the Kitten Weight Chart by Age.
Is the ideal weight range right for large breeds like Maine Coons?
Not always. The ideal range here is for typical domestic cats, and large breeds like Maine Coons and Ragdolls naturally run heavier at a healthy weight. The body condition check above (ribs, waist, belly tuck) is a more reliable way to judge an individual cat than any single ideal number.
When do kittens reach their full adult weight?
Most domestic cats reach their full adult weight by 12 months. Larger breeds like Maine Coons and Ragdolls may continue growing until 18–24 months. Males typically weigh 2–4 lbs more than females of the same breed.