Cat Weight Calculator
A scale reading alone cannot tell you whether your cat is at a healthy weight. Use a recent 9-point body condition score (BCS), ideally assessed by your vet.
How this estimate works
For scores 6–8, reference weight = current weight ÷ (1 + 0.1 × (BCS − 5)). This uses the approximate 10% excess weight per point above 5 in AAHA’s body condition guidance. Scores 4–5 are treated as the ideal range. No target is calculated for scores 1–3 or 9, where an individual assessment is especially important.
This is not a BMI measurement or a feeding prescription. It does not assess muscle loss, illness, or your cat’s build. Confirm any target with your vet before changing food amounts.
How to use the weight calculator
Have two details ready: a recent weight and a body condition score from the nine-point scale. Choose the correct unit before entering the number. A weight recorded in pounds should not be entered as kilograms.
- Confirm that your cat is a healthy adult and is not pregnant or nursing.
- Enter the current weight and select kilograms or pounds.
- Select the recent body condition score, preferably one assessed by your veterinarian.
- Calculate the estimate and read the explanation beside the number.
If you do not know the score, stop there and ask your clinic to assess it. Choosing a score just to get a result makes the estimate less useful.
What the result means
Body condition describes body fat; the scale records total weight. AAHA recommends considering weight, body condition, muscle condition, diet and an examination together. An overweight cat can also have muscle loss. That is why this tool cannot identify a healthy weight from a scale reading alone. See AAHA’s nutritional assessment guidance.
At scores 6–8, this calculator applies the approximate relationship of 10% excess weight for each point above 5. It divides the current weight by 1.1, 1.2 or 1.3 respectively. Scores 4–5 receive an ideal-range explanation; scores 1–3 and 9 receive no numerical target. These are limits of this tool, not a substitute for an individual assessment.
A worked example
For an illustrative 6 kg adult cat with a score of 7/9, the calculation is 6 ÷ 1.2 = 5 kg. The displayed 5 kg is a reference point to discuss with your vet. It does not tell you how much to feed or how quickly weight should change.
Make the result useful at your appointment
Write down the date, weight, unit and who assessed the score. Bring the food packaging and a note of meals, treats and supplements. Ask your vet whether the score is current, whether muscle condition needs attention, and what monitoring schedule suits your cat.
A record reading “6 kg, September 28, BCS 7/9 at the clinic” gives more context than a screenshot of “5 kg.” Keep the original measurements with the estimate.
Frequently asked questions
Is this a cat BMI calculator?
No. It uses weight and a nine-point body condition score. It does not use body length or girth measurements.
Can I use a five-point score?
No. Entering 4/5 as 4/9 changes the meaning. Ask your vet for the corresponding assessment on the nine-point scale.
Can it calculate food portions?
No. The result contains no calorie or portion recommendation. Confirm any feeding changes with your veterinarian.
Are my entries saved?
The calculator processes entries in your browser and does not submit them. Save any notes you want to bring to your appointment yourself.
By The Cats Hub editorial team. Updated September 28, 2026.