Body condition score (BCS) is a 1 to 9 number assigned by hand, and 1 point is worth roughly 10 percent of body weight. A cat at 8 carries about 30 percent more fat than it should, which on a 5.0 kg frame is 1.5 kg of excess. The 3 touch points below give you that number in 30 seconds, once every 4 weeks, with no scale.
Why one weight number says nothing
A 5.5 kg cat can be lean or 20 percent overweight, and the scale cannot tell you which. BCS measures the fat layer over bone, so it travels across frame sizes: a 3.2 kg Siamese at 5 and a 6.4 kg Maine Coon at 5 are both correct. Use weight for direction over time and BCS for where the cat stands today. Weigh once a month, score once a month, write both down. Kittens under 12 months are scored on a length-based chart instead, because a growing frame is not a fat frame; that version is in kitten body condition check.
Touch point 1: the ribs
Lay a flat palm on each side of the chest and stroke back, no pressing. At 5 you feel every rib through a thin cover, like the back of your hand. At 3 the ribs stand up like knuckles and the skin between them feels hollow. At 7 you need light pressure to count 6 or 7 ribs. At 8 or 9 your fingers sink into a soft layer before they reach bone, and at 9 you cannot find the ribs at all.
Touch point 2: the waist from above
Stand over the cat while it stands square on all 4 feet. Behind the last rib there should be an inward curve on both sides, about 1 to 2 cm narrower than the chest wall. A straight line from ribs to hips scores 6. A bulge that widens past the ribs scores 7 or more. A deep hourglass with visible hip bones scores 4 or below.
Touch point 3: the belly line from the side
At eye level with the cat, the belly should tuck up 1 to 2 cm from the rib cage toward the hind legs. A level belly line is 6, a sagging one is 7 to 9, and a sharp hollow tuck with a pinched flank is 3 or below. In an older cat a pendulous belly can also be loose skin after weight loss, so check the ribs before you call it fat.
From score to kilograms
Worked example. A cat reads 14.3 lb on the clinic scale. Convert to kilograms: 14.3 ÷ 2.205 = 6.49 kg. Ribs unfindable, no waist, sagging belly line: BCS 8. That is 3 points above 5, so 3 × 10 = 30 percent over ideal body weight.
Ideal weight = current weight ÷ 1.30 = 6.49 ÷ 1.30 = 4.99 kg, round to 5.0 kg. Excess fat = 6.49 − 5.0 = 1.49 kg, which is 23 percent of the cat's current weight. A cat at 9 goes to 4 points over, a 40 percent margin, and the divisor becomes 1.40: 6.49 ÷ 1.40 = 4.64 kg.
| BCS | Ribs under a flat palm | Waist from above | Percent vs ideal | Weight if ideal is 5.0 kg |
|---|---|---|---|---|
| 3 | Sharp, like knuckles | Deep hollow, hips bony | −15% | 4.25 kg |
| 4 | Easy to count, thin cover | Clear curve | −10% | 4.5 kg |
| 5 | Felt like the back of a hand | Visible curve, 1 to 2 cm | 0% | 5.0 kg |
| 6 | Felt with light pressure | Almost straight | +10% | 5.5 kg |
| 7 | Hard to find, 6 or 7 counted | Slight bulge | +20% | 6.0 kg |
| 8 | Only with firm pressure | Bulge wider than chest | +30% | 6.5 kg |
| 9 | Not findable at all | Round, no waist | +40% | 7.0 kg |
Turning the score into a calorie target
Resting energy requirement (RER) = 70 × body weight in kg raised to 0.75. On the 5.0 kg target: 5.0^0.75 = 3.34, so RER = 70 × 3.34 = 234 kcal per day. A loss plan runs at 0.8 × RER = 187 kcal per day, and that figure is set on the target weight, never on the current 6.49 kg. On a 380 kcal per 100 g kibble, 187 kcal is 49 g; on a 100 kcal per 100 g pâté it is 187 g, split into 3 or 4 weighed meals.
Safe loss is 0.5 to 1 percent of body weight per week, which is 32 to 65 g on this cat. At 32 g a week, 1.49 kg takes 46 weeks; at 65 g it takes 23 weeks. Faster than 1.5 percent a week risks muscle loss and hepatic lipidosis, so most vets take the slow lane and re-score every 4 weeks. Cold weather lifts maintenance by 10 to 20 percent, so a plan written in July is 20 to 35 kcal short in January; the seasonal adjustment is in winter calorie needs.
Long hair, senior muscle, and the 2 errors
A full coat hides 1 to 2 points. Wet the fur down or slide a hand under it, and score on bone, not silhouette. Cats past 10 lose muscle before fat, so a BCS 5 cat can still have a bony spine and flat hips; that is muscle condition, scored separately, and it matters more than the fat number in a sick cat.
The 2 common errors are scoring by feel of the fur and scoring a cat that is sitting hunched, which fakes a waist. Score standing, from above and from the side, and have a second person confirm the rib call the first 3 times.
When the score is too low
A BCS 3 or 4 cat, or any cat that drops 1 point in 3 months, needs a vet visit before a diet change. Weight loss of 10 percent in 6 months is a clinical sign, not a diet result: dental pain, hyperthyroidism, chronic kidney disease (CKD), diabetes, and intestinal disease all present this way. Bring the weights, the dates, and the food label in grams per day. A first workup with blood work and a thyroid panel is the bulk of the bill, and the cost tool turns that visit into a yearly figure before you book it.
What to do this week
- Score the cat today on all 3 points, standing, and write the number and the date on the food bin.
- Weigh on the same scale at the same time of day, monthly, and record to 10 g.
- If BCS is 7 or above, set calories at 0.8 × RER of the target weight before changing the food.
- Weigh the ration in grams for 7 days; a cup scoop varies 70 to 110 g by kibble shape.
- Re-score at 4 weeks. Two flat months means cut the ration 10 percent, not 30.
Frame size and coat length change how a cat looks, never how it feels under a hand. Score the ribs, then let the arithmetic set the bowl. A feeding plan built on a guessed weight fails in month 2, which is where most diet attempts die.
Terms mentioned in this article
Frequently asked
Can I score my cat without a scale?
Yes. The 3 touch points need only your hand and a look from above and from the side, and they land within 1 point of a vet's score after 3 or 4 tries. Keep a scale for the monthly weight, because a 1 point change equals about 10 percent of body weight and that is 300 to 600 g on most adult cats, enough to confirm the hand.
Is 1 point really 10 percent of body weight?
It is the working rule most clinics use: each point above 5 is treated as about 10 percent over ideal weight, so a BCS 8 cat is roughly 30 percent heavy and the ideal weight comes from dividing by 1.30. It is an estimate, not a measurement, and a very large or very small frame drifts by a few percent either way.
How fast should an overweight cat lose weight?
Aim for 0.5 to 1 percent of body weight per week, which is 32 to 65 g on a 6.5 kg cat, and never faster than 1.5 percent. Losing quicker strips muscle and can trigger hepatic lipidosis, especially if the cat stops eating for 2 or 3 days. Re-score every 4 weeks and cut the ration by 10 percent when the score stops moving.