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BMI Calculator

BMI Calculator calculates BMI for adults based on entering some of your information, including gender, height, and weight, to determine your height to weight ratio.

Height (ft)
Height (in)

Introduction of BMI and BMI Calculator

BMI, or Body Mass Index, is the value derived from an individual’s height and weight. It is a widely used metric for categorizing a person as obese, overweight, average, or underweight. BMI is calculated in the units of kilogram per meter square, as it is measured by dividing the square of a body's height by a body mass. To avoid the hassle of manual calculation and quickly figure out the BMI, SmallSEOTools has introduced the BMI Calculator that provides you with accurate results in a matter of instances. Now you can calculate BMI with the help of our online service without following intricate methods.

How to Calculate BMI for Adults

By following the steps below, you can calculate your Body mass index using our BMI calculator.

  • Step1: Select Gender
  • Step2: Enter your height in ft/in or Cm
  • Step3: Enter Weight in Lbs or KGs 
  • Step4: Now hit the “Calculate BMI” button

How to calculate BMI for children

  • Step1: Select the gender
  • Step2: Select the age
  • Step3: Enter your height in ft/in or cm
  • Step4: Enter weight in lbs or kgs 
  • Step5: Now hit the “Calculate BMI” button

What Does Your BMI Mean?

As mentioned before, the value of your BMI describes whether you are underweight, normal weight, overweight, or obese. Generally, you can consider yourself one of them if your BMI falls between the given ranges:

  • Obese = BMI is equal to or greater than 30
  • Overweight = BMI is equal to or between 25 - 29.9
  • Normal Weight = BMI is equal to or between 18.5 - 24.9
  • Underweight = BMI less than 18.5

BMI Table for Adults


BMI Range

Severe Thinness


Moderate Thinness


Mild Thinness

17 – 18.5


18.5 – 25


25 – 30

Obese Class 1

30 – 35

Obese Class 2

35 – 40

Obese Class 3


Risks Associated with Being Overweight

Being overweight leads a person to several health issues. You can face the following risks with being overweight:

  • High blood pressure
  • High LDL cholesterol
  • Heart disease
  • Type 2 diabetes
  • Breathing issues
  • Mental disorders
  • Anxiety
  • Depression
  • Body pain

Risks Associated with Being Underweight

Being underweight can also lead to medical problems, just like obesity. The significant risks you can face being underweight are:

  • Sickness
  • Anemia
  • Feeling tired
  • Slow growth
  • Premature birth
  • Irregular periods
  • Skin and hair problems 

How Do I Calculate BMI Manually?

There are two main formulas to calculate BMI, which are English BMI and Metric BMI. Let’s take a look at each of them and understand how they work with the help of an example. 

English BMI Formula:

703 x weight (lbs.)/ height2 (inches)

With this formula, you need to multiply the weight in lbs. by 703 and divide it by the height squared in inches. For instance, if a person’s weight is 160 lbs. and height is 70 inches, then his BMI would be calculated as:

703 x 160/ 702

BMI = 22.9

Metric BMI Formula:

Weight (Kgs)/ height2 (meters)

The metric BMI formula is similar to the English BMI formula, but the only difference between them is the measurement units. If a person’s height is 1.8 meters and weight is 100 kg, then with the metric BMI formula, his BMI would be calculated as:


BMI = 30.9

BMI Calculator for Adults and Children

The genetics and body measures vary from person to person due to the difference in age ranges. Therefore, the Body Mass Index is interpreted differently for both adults and children. The BMI Calculator by SmallSEOTools has been designed to allow users to find their BMI per their age range. If you choose a BMI calculator for adults to calculate the BMI of a teenager, then obviously, you can't get accurate results. However, if you choose the right tool and calculate it as per the age range of your child, you can get your hands on accurate results without any hassle. The BMI calculator for children and adults is based on smart algorithms that depict your selected mode and age and calculates BMI precisely.

BMI Calculator for Adult Men and Women

Just like adults and children, the BMI between men and women also varies as they don’t have identical body measures and genetics. On average, women are short-heightened; therefore, their BMI cannot be treated similarly to men. Our online service allows you to calculate BMI for women and BMI for men distinctly to find specific results. You don’t need to go through the hassle of the registration process for using our BMI calculator. You can entirely rely on the results generated by our online BMI calculation tool, as it lets you adjust your age and gender to find the exact Body Mass Index.

Limitations of BMI

Experts have raised their fingers over the reliability of the Body Mass Index due to several reasons. There are certain limitations of BMI due to which they have termed it an inaccurate measure for analyzing body fat. Some of its limitations are:

  • BMI charts don't distinguish between the gender of the individuals. Males are prone to gaining more muscle mass, whereas females have more fat mass, which makes BMI an unrealistic measure.
  • BMI doesn’t take body fat percentage or muscle mass into account.
  • BMI doesn’t specify water weight and bone mass while calculating the relation between height and weight.

Who Shouldn’t Use a BMI Calculator?

BMI wouldn’t be an accurate representation for many people, such as pregnant women, athletes, young children, and bodybuilders. This is because a BMI calculator considers weight just as a number; however, for some people, the weight could be heavy due to muscles rather than fats.

For instance, athletes and bodybuilders have a high muscle mass that results in a much higher BMI. But this doesn’t mean they are open to facing health issues like obese people. Similarly, during pregnancy, the mass and body of a woman change, which makes the BMI calculator ineffective for them. Moreover, BMI calculation will show low BMI for children as they are likely to lose mass. But they shouldn’t be considered underweight by BMI calculation as they are still at a growth stage.


  • When Should I Be Concerned with My Child's Weight?

If your child is losing weight, getting weak, staying ill for ample time, or has a lasting illness, you should be concerned and talk to your doctor.

  • When Should I Start Checking my BMI? How Often Should I Check?

You can start checking your BMI whenever you want. For children, it must be checked for the ones who are 2 years old. You can check your BMI once every four weeks.

  • What is My Ideal Weight?

Your ideal body weight depends upon your sex, age, and height. There’s no specific figure of ideal weight for all individuals.

  • What is My Child’s Ideal Weight?

Your child’s ideal weight is also dependent upon similar factors, which are sex, age, and height.

  • Is Muscle Counted in BMI?

No! The muscle mass is not taken into account for calculating BMI,

  • How Can I Reduce My BMI?

You can take several actions to reduce your BMI. You should ditch highly processed foods, increase fiber intake, make use of protein, etc., to reduce your BMI.

  • How Can I Help My Child Reduce his/her BMI?

You can help your child in reducing BMI by encouraging him/her to participate in physical activities daily. You can make them follow strict diets and take healthy meals.

  • BMI Reduction: How Long Will It Take?

You can reduce between 1-3% of your body fat per month. BMI reduction depends upon how seriously you take it and how much effort you are investing. You can start seeing a reduction in BMI by paying proper attention and taking necessary actions. 


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