Cat BMI Tools

Created By : Prasanna
Reviewed By : Phani Ponnapalli
Last Updated at : May 1,2023

Cat BMI Tools is a free tool that helps you in calculating the Body Mass Index of your furry friend. Everyone loves fluffy cats but sometimes your furry friend may get a little too fluffy. If you sometimes wonder whether or not your pet cat is of the correct weight or not, the Cat BMI Tools will help you get the exact answer to your question. With the help of only two measurements, the cat BMI calculator will let you know whether or not your cat is overweight in just a matter of a few seconds.

Rib cage circumference
Length of the lower back leg

Cat BMI Tools: BMI stands for Body Mass Index. It is a measurement scale designed to find out if someone is underweight, fit, or overweight. These scales are different for different species. In the case of cats, the BMI range lets you know what is the ideal weight for your fluffy pet. For a detailed account of how to calculate the cat's Body Mass Index and how to make your cat lose weight, refer to the article given below.

FAQs on Online Cat BMI Tools

1. What is BMI?

BMI is the Body Mass Index. It is a measuring scale that determines whether your cat is underweight, normal weight, overweight or obese.

2. What measurements do I require in order to calculate the BMI of my cat?

You need to measure the Rib Cage and Leg Length for calculating the BMI of your cat.

3. How to calculate the BMI of my cat?

You can calculate the BMI of your cat by using the following formula, FBMI = ((( Rib Cage / 0.7062) - Leg Length ) / 0.9156 ) - Leg Length

4. What is the ideal BMI range for cats?

The ideal BMI range for cats is 15 - 29.9.

Measurements required for Cat BMI Tools

This calculator takes into account the Feline Body Mass Index (FBMI) in order to calculate the BMI. FBMI is based on the proportions of your furry friend. There are 2 measurements required in order to calculate the FBMI. Refer to the information given below for a detailed account of how to take the measurements required to calculate the FBMI.

  • The cat needs to be standing and its head should be in an upright position.
  • The first measurement needs to be taken from the rib cage. You can do it by measuring the 9th rib cage which is located near the front legs of your furry pet.
  • The second measurement needs to be taken from the lower back leg i.e. from its knee to the ankle.
  • Then all you need to do is enter these measurements into the Cat BMI Tools and the results will be on your screen within seconds.

How to Measure Cat BMI?

The formula that is used in order to calculate the Cat BMI is as follows:

FBMI = ((( Rib Cage / 0.7062) - Leg Length ) / 0.9156 ) - Leg Length

All you need to do in order to calculate the FBMI of your cat is take the measurements according to the aforementioned steps and then put the values in the above given formula. You must know that there is not a specific weight that is considered healthy for your furry friend. The ideal BMI is given ranges. You can learn more about these ranges in the section given below.

FBMI Range Chart

There are 5 different ranges to take into consideration while calculating the BMI of humans. However, in the case of cats, there are 4 ranges that tell whether your cat is underweight, fit, or overweight. These BMI ranges are given below:



< 15


15 - 29.9

Normal Weight

30 - 42


> 42


The Cat BMI Tools not only helps you find out whether your cat is underweight, normal weight, overweight or obese but it also helps you realize what the ideal weight and measurements of your furry friend should be in order to be considered healthy and fit. You can get an exact idea about this in the examples illustrated later in the article.

How to Help the Cat Lose Weight?

In case your furry friend has become a victim of your pampering nature and has gotten overweight, there are certain steps that you can take in order to get your cat back in shape. These steps have been listed below:

  • The first step is to monitor what your cat eats. Try and tighten your hand on what you give your furry friend in the form of treats. Make sure your cat eats healthy.
  • Always keep in mind that starvation never works for humans as well as cats. Crashing the diet drastically will result in health issues and nothing else.
  • You can substitute dry foods with canned food that has higher carbohydrates and protein content. Dry foods will only do to your furry friend what junk food does to us.
  • The best way to make your cat lose weight is to exercise. Now you don’t need to get your cat a gym membership, all you need is to play with your furry friend on a daily basis. The playtime will result in healthy exercise hours.

Cat BMI Calculation Examples

Example 1:
A cat has a rib cage circumference of 14 inches and its lower back legs are 2 inches. Calculate the BMI of this cat.


The formula for calculating the BMI if a cat is: FBMI = ((( Rib Cage / 0.7062) - Leg Length ) / 0.9156 ) - Leg Length


Rib Cage = 14 inches = 35.56 cm

Leg Length = 2 inches = 5.02 cm

According to formula,

FBMI = ((( 35.56 / 0.7062 ) - 5.08 ) / 0.9156 ) - 5.08

FBMI = 44.36 = 44.4

Therefore, the BMI of the cat is 44.4 and hence it is obese.

Example 2:
The cat in the above example is obese. Find out the target rib cage circumference in order for it to be considered healthy.


The BMI of the cat is 44.4 which is considered obese. Now, according to the FBMI range, a healthy value is between 15 - 29.9. In order to calculate the target rib cage circumference, we take the BMI as 29.


BMI = 29

Leg Length = 2 inches = 5.08 cm

According to formula,

Rib Cage = ((( FBMI + Leg Length ) * 0.9156 ) + Leg Length ) * 0.7062

Rib Cage = ((( 29 + 5.08 ) * 0.9156 ) + 5.08 ) * 0.7062

Rib Cage = 25.6 cm which is approximately 10 inches.

If difficult calculations in the subject of mathematics and biology are troubling you, you can take the help of to get your answers within seconds.