Is my dog a
healthy weight?
Enter your dog's weight and height at the withers to calculate their BMI and see where they sit on the body condition scale — instantly.
Uses the standard weight ÷ height² formula · Mapped to Body Condition Score · Always confirm with your vet
How to measure your dog accurately
The BMI calculation is only as reliable as the two measurements you put in. Here is how to get both right, even with a wriggly dog.
Weigh your dog on a flat scale
For dogs under about 15 kg, a baby scale or kitchen scale placed on a flat floor gives accurate results. For larger dogs, stand on a bathroom scale holding your dog, note the combined weight, then weigh yourself alone and subtract. Many vet clinics and pet shops have walk-on scales your dog can step onto directly. Always use the same scale each time for consistency — different scales can read slightly differently.
Measure height at the withers
Stand your dog on a hard, flat surface. The withers is the highest point between the shoulder blades — not the top of the neck or head. Ask your dog to stand squarely with all four paws on the floor and head held at a natural level. Place a ruler or book flat on the withers and mark the wall at that height, then measure from the floor to the mark. For wiggly dogs, a second person helping hold the dog still makes this much easier.
Enter both values and read your result
Enter the weight and withers height in your preferred units (kg/lbs and cm/inches). The calculator will compute your dog's BMI, display the category with a colour-coded scale, show the equivalent Body Condition Score range, and give you tailored advice based on where your dog falls. Use the result as a starting point for a conversation with your vet if anything concerns you.
Dog BMI and body condition explained
Body Mass Index was originally developed for humans but applies to dogs because the fundamental relationship between weight and skeletal frame size holds across mammals. A dog that weighs more relative to its height is carrying more mass, and beyond a certain threshold that excess mass is fat rather than muscle or bone.
Veterinary professionals most commonly assess body condition using the Body Condition Score (BCS) — a hands-on, visual assessment scored on a scale of 1 to 9, where 4–5 is ideal. BMI and BCS correlate well in most dogs and our calculator maps your BMI result to the equivalent BCS range so you can speak the same language as your vet.
Where BMI and BCS diverge is in very muscular breeds. A Staffordshire Bull Terrier or a working Greyhound may produce a BMI in the overweight range while actually being at a perfectly healthy body fat percentage. In these cases, the hands-on BCS check — running your hands along the ribs, assessing waist definition from above, and checking for a belly tuck from the side — is more informative than BMI alone.
What each BMI category means for your dog
The BMI scale has four zones. Each one tells a different story about your dog's current health and what, if anything, needs to change.
Underweight (BMI under 18.5 · BCS 1–3)
Ribs, spine, and hip bones are prominently visible and easy to see from a distance. The dog has little to no fat covering and may lack muscle mass as well. Causes include insufficient food, poor nutrient absorption, intestinal parasites, dental pain that prevents eating, or underlying illness. An underweight dog should be seen by a vet to identify the cause before simply increasing food.
Healthy weight (BMI 18.5–25 · BCS 4–5)
Ribs are easily felt with gentle pressure but not visible. There is a visible waist when viewed from above, and a gentle upward tuck of the belly from the side. The dog has a lean, athletic appearance. This is the target zone — maintaining it throughout life is associated with reduced joint disease, fewer metabolic problems, and a significantly longer lifespan compared to overweight dogs.
Overweight (BMI 25–30 · BCS 6–7)
Ribs are palpable but with noticeable fat deposits. The waist is barely visible and the belly is slightly rounded. Overweight dogs tire more quickly on walks and often have reduced enthusiasm for exercise — which then makes the weight problem worse. A modest reduction in daily food (10–15%) combined with longer daily walks is usually sufficient to reverse mild overweight within 2–3 months.
Obese (BMI over 30 · BCS 8–9)
Ribs cannot be felt beneath a thick fat layer. The waist is absent and there may be fat deposits over the neck, shoulders, and base of the tail. Obese dogs are at high risk of osteoarthritis, type 2 diabetes, respiratory problems, and early death. Obesity at this level typically requires a supervised veterinary weight-loss plan — do not attempt rapid weight loss through severe restriction without professional guidance.
How to help your dog reach a healthy weight
For overweight dogs: reduce first, then move more
The most effective approach is a combination of dietary restriction and increased activity, but the order matters. Start by reducing food portions by 10–15% — this alone produces meaningful results without the injury risk of suddenly increasing exercise in a dog that is deconditioned. After two weeks of successful calorie reduction, gradually extend daily walks by 10–15 minutes per week.
Measure food by weight using a kitchen scale rather than cups. Switch from high-calorie treats to low-calorie alternatives like carrot sticks, cucumber, or commercial low-fat treats. Count all food including treats, dental chews, and table scraps as part of the daily total.
For underweight dogs: increase gradually
Do not try to rapidly catch an underweight dog up by doubling their food. Increase portions by 10% per week and monitor closely. If the dog is not gaining weight despite eating well, a vet check is needed to rule out malabsorption, parasites, or illness. Highly digestible, nutrient-dense foods are preferable to large volumes of low-quality food.
- Weigh your dog fortnightly and track the trend
- Use the food calculator to recalculate portions as weight changes
- Aim for 1–2% body weight change per week maximum
- Recheck BMI every 4–6 weeks during a weight management programme
Five ways to tell if your dog is the right weight
No calculator replaces the hands-on body condition check. These five assessments take under a minute and give you a reliable read on your dog's condition between vet visits.
The rib test
Run your flattened hands along both sides of your dog's ribcage with light pressure. At a healthy weight, you should feel each individual rib without pressing hard, but the ribs should not be prominently visible. If you cannot feel the ribs at all through a fat pad, your dog is overweight. If the ribs are sharply prominent and visible from across the room, your dog is underweight.
The waist check (from above)
Stand above your dog and look down at their back. A healthy-weight dog should have a clear hourglass shape — wider at the chest and hips, noticeably narrower at the waist just behind the ribcage. A dog that is the same width from shoulders to hips, or wider at the middle, is overweight. Some deep-chested breeds like Greyhounds have a more exaggerated tuck that is completely normal for their breed.
The belly tuck (from the side)
Look at your dog from the side. The abdomen should tuck upward as it goes from the ribcage toward the hind legs — a gentle concavity. A sagging, rounded belly with no upward tuck is a reliable sign of excess abdominal fat. In contrast, an extreme tuck with visible hip bones and spine is a sign of being underweight. Both extremes are worth addressing.
Exercise tolerance
A dog at a healthy weight should be able to complete their usual walk without heavy panting, excessive rest breaks, or reluctance to continue. Overweight dogs tire noticeably faster and may sit or stop mid-walk. If your dog is lagging behind on walks they used to handle easily, or panting heavily after modest exertion, weight is a likely contributor — though a vet check to rule out respiratory or cardiac causes is also warranted.
Energy and coat condition
Dogs at a healthy weight tend to have a shiny, full coat and generally good energy levels appropriate for their age and breed. Overweight dogs often have dull coats — excess body fat can disrupt the balance of fatty acids available for skin and coat health. Underweight dogs may have dry, thin, or patchy coats as the body prioritises energy over coat maintenance. These are secondary signals but useful ones to notice.
Frequently asked questions
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