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Dog BMI Calculator

Created by Michael Darcy
Reviewed by Dominik Czernia, PhD and Jack Bowater
Last updated: May 03, 2024

All pet owners want to keep their little friends happy, but we might end up overdoing this at times - and this dog BMI calculator is here to help you check if the bowl isn't a bit too full. We don't blame you - it takes a lot of self-control to resist your pup when he asks you so nicely for a treat. It's no surprise then that we find ourselves asking "Why is my dog gaining weight"?

If we can estimate the dog age in human years, why not use another scale commonly used for people? BMI is a prevalent measure of how one's body mass compares to one's height. We've already created a cat BMI calculator, so there's no reason why other four-legged friends wouldn't be able to use this scale also. If you want to find out if your dog is overweight, and if that's the case, how to help your dog lose weight - read on!

Is my dog overweight? Dog BMI formula

Although someone could argue that it's obvious when a pup is a tad too chubby, that's not always the case. Even so, numbers can be reassuring, and you can use them as guidelines telling you how far your dog is (if at all) from its ideal weight.

There are two ways of telling if your dog is overweight:

  1. Canine body condition score is the most popular one. The Pet Food Manufacturer's Association created very detailed and user-friendly charts that can help you check if your pet's within healthy range just by inspecting it. There are 5 categories you pup may fall into:

    • Very thin: no fat can be felt under the skin. Ribs, hip bones, and spine are clearly visible with noticeable loss of muscle.
    • Thin: very little fat can be felt under the skin. Ribs, hip bones, and spine are easily spotted.
    • Ideal: a small amount of fat can be felt. Ribs, hip bones, and spine are easily felt (not seen!) with a visible waist. Congratulations, your dog is at a healthy weight.
    • Overweight: a layer of fat is present on the belly and at the base of the tail. Ribs, hip bones, and spine are hard to feel with a barely visible waist.
    • Obese: there are fat pads on the lower back and the tail base. Ribs, hip bones, and spine are under a thick layer of fat and difficult to feel. No waist is visible, and the belly may sag.
  2. Body Mass Index is less popular due to the difficulty in finding the perfect value. Although people come in all shapes, ages, races, and such, we managed to establish that the healthy range is between 18.5 and 24.9, and this result is accurate for most of us. It is much trickier to do that for dogs as the size and build differences between breeds are significant. Not only that, but we also can't forget about mongrels, whose mix of different breeds mean they need a different range. Therefore, there isn't yet a standardized method for computing canine BMI. The typical dog BMI formulae are:

BMI=weight×703height2\text{BMI} = \frac{\text{weight} \times 703}{\text{height}^2}

which is simply the formula used for evaluating human BMI, for example, in BMI calculator. Then the value is compared with the acceptable range for the considered breed using the dog BMI chart. The numbers can get pretty large; e.g., for an Australian Shepherd, the healthy dog BMI is between 86 and 88.

BMI=weightheight\text{BMI} = \frac{\text{weight}}{\text{height}}

which is the formula used in our dog BMI calculator. The resultant values in this dog BMI chart are typically less than 10, and hence they look less intimidating than those obtained from the above equation.

Both formulae are given for calculations in inches and pounds, so you may need to convert the units - or use our dog BMI calculator to save you the hassle. 😃

How to interpret results from the dog BMI calculator?

We've used the reference values provided by the American Kennel Club to obtain healthy BMI ranges for 157 breeds. They may also be helpful if you're wondering how much your dog should weigh.

After inputting your pup's height and weight, you will see the BMI value and how it compares to the healthy range. For example, if you considered a 20.9-inch dog with a mass of 40 lbs, its BMI would be 1.93. This is a good result for Samoyed, but a Boxer this size would be underweight.

If your pet is a mutt or of any other breed that isn't listed, it's generally agreed that the BMI should be equal to or less than 3. With that being said, bear in mind that this may not be the case for larger dogs.

Most importantly, you should remember that ultimately, the BMI is just an estimate. It is worth checking the results with the canine body condition score and consulting the vet if you're in doubt. They will be able to tell you for sure if your dog is overweight or if there's a risk of pet obesity.

Why is my dog gaining weight? Possible causes

Before searching how to help a dog lose weight, it's sensible to think about the causes as it may make it easier to deal with the issue. Several reasons may explain why your dog is gaining weight:

  • Lack of exercise is one of the obvious "culprits" responsible for pet obesity. Just like humans, dogs need physical activity. It may be difficult to take your pup on multiple long walks daily, especially if you have a busy schedule, but try to get your four-legged friend moving as much as possible. This can also help compensate for the calories from treats if you can't bring yourself to say "No". If you'd like to find out how much exactly your pup should be eating, visit the dog calorie calculator.
  • Malnutrition is strongly intertwined with the above. If your dog eats more calories than it needs, the excess energy will be stored as body fat. It's also important to pay attention to the food you give to your fluffy friend. Good quality food will not only provide all the necessary nutrients but also keep your pet fuller for longer. This could reduce food consumption and also potentially save you a visitor at your table during dinner.
  • Age, breed, and neutering may all play a role. Older and neutered dogs may be less energetic, so eating as much as they used to (or even more) can lead to weight gain. Some breeds (e.g., Golden Retrievers) are also more likely to experience obesity, so even if your pet was at a healthy weight previously, a combination of those factors might lead to excessive body mass.
  • Hormonal imbalances, genetics, and diseases can also cause dogs to gain weight. In fact, sometimes, this is the only symptom visible to the owner. This is why it's essential to consult the vet before trying to handle your pet's obesity.

How to help your dog lose weight?

The BMI suggests that your beloved pup is overweight, and you looked up how much your dog should weigh to estimate how far it is from the healthy range. The vet ruled out any conditions, and now you're wondering How to help my dog lose weight? Well, there are several things you can do:

  • Cut back on treats, and if you'd like to keep them, opt for healthier choices. Your pet may not be over the moon initially, but he'll get used to it eventually. Moreover, most dogs will appreciate other rewards, such as playtime with you or a simple petting!

❗ 🍫Remember, chocolate can be toxic to dogs! Dog chocolate toxicity calculator talks about it in more detail.

  • If you can, consider getting your dog a buddy to play with. Not only it's additional exercise, but also tons of fun! It's a triple win if this friend also needs a hand in staying in shape. Alternatively (or better yet, additionally), you can try to increase the number or length of daily walks.
  • Ensure a good quality of food. It will keep your dog's tummy full for longer. Nutrients are crucial in maintaining good health, even if there's no issue with weight.
  • In addition to the above, portion control may be a good idea. Using your eyes to estimate the amount of food may be very misleading, so it's safer to weigh it and count calories.
  • If you feel like cheating a bit and have enough space, you can try placing the bowl upstairs - this way, your dog will have to make some effort before eating!

Managing your fluffy friend's weight may be tricky, but it'll definitely pay off!


How to calculate BMI for dogs?

To calculate the dog BMI:

  1. Weigh your dog. If in kg, divide by 0.45 to get lbs.
  2. Measure its height from the shoulder. If in cm, divide by 2.54 to obtain inches.
  3. Divide weight by height to get the BMI.

Remember that the healthy range is different for every breed, and it's best to check the canine body condition score for comparison.

How to make a dog gain weight?

There are several things you can do to help your pup bulk up:

  • Opt for high-calorie food.
  • More exercise can help build muscle but remember to increase the food portion size accordingly.
  • You may want to consider changing the feeding schedule, e.g., give your dog smaller portions, but more frequently.
  • Try to entice your dog by choosing tasty snacks or toppers such as wet food. Some pups are also fond of peanut butter! (as long as it's without Xylitol)

Why is my dog losing weight?

Several reasons may cause weight loss in dogs:

  • Diet - Your dog may be getting fewer calories than it needs. Think if you've changed its food lately or incorporated more activity.
  • Age - Older dogs tend to lose their muscle mass, which is a significant part of your pet's weight.
  • Diseases - Dental disease, abdominal pain, diabetes, or more severe ones, including cancer, can cause your dog to lose weight. Make sure to consult your vet.

How often to feed a dog?

Most experts recommend twice daily. However, there's no "one size fits all", so it may not be the right choice for your dog. For example, working dogs require more energy so free-feeding may be a better option which doesn't necessarily lead your pet to obesity. We recommend experimenting to see what works best for your pup.

Michael Darcy
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