BMI Calculator to Check Your Body Mass Index

BMI Calculator to Check Your Body Mass Index

BMI Calculator




What is BMI Calculator

  • Body mass index (BMI) is a measure of body fat based on height and weight that applies to adult men and women using the BMI Calculator.
  • BMI is the main indicator used to measure the index of obesity.


Steps to Use BMI Calculator

  1. Enter Your Age & Select Your Gender.
  2. Put your weight and height using standard or metric measures.
  3. Compute BMI and your BMI will appear below.
  4. To calculate BMI, multiply weight in pounds by 703, divide by height in inches, and then divide again by height in inches or you can divide weight in kilograms by height in meters squared.


Healthy BMI Range

Here are Healthy BMI Range Tables are given to calculate Body Mass Index (BMI) using BMI Calculator.

BMI (Kg/m²) Class
Less than 18.5 Underweight
Between 18.5 - 25.0 Normal Weight
Between 25.0 - 30.0 Over Weight
Between 30.0 - 35.0 Class 1 Obesity
Between 35.0 - 40.0 Class 2 Obesity
40.0 or over Morbid Obesity or Class 3 Obesity


BMI Normal Range Table


BMI Calculator Chart Ranges


Underweight: BMI less than 18.5 kg/m²

  • A BMI of less than <18.5 indicates that you are underweight, so you may need to put on some weight.
  • You are advised to ask your doctor or a dietitian for advice in BMI Calculator.


Normal Weight: BMI ranges between 18.5–24.9 kg/m²

  • A BMI range of 18.5-24.9 indicates that you have a healthy weight according to your height.
  • You lower your risk of developing serious health problems by maintaining a healthy weight in the BMI Calculator.


Overweight: BMI range between 25–29.9 kg/m²

  • A BMI range of 25-29.9 indicates that you are slightly overweight.
  • You may be advised to lose some weight for health reasons.
  • You are advised to talk to your doctor or a dietitian for advice using BMI Calculator.


Obesity Definition BMI over 30 kg/m²

  • A BMI of over 30 indicates that you are heavily overweight.
  • Your health may be at risk if you do not lose weight.
  • You are advised to talk to your doctor or a dietitian for nutrition advice in BMI Calculator.


Abdominal Obesity

  • Abdominal obesity is defined as a waist circumference of more than 102 cm (40 inches) in men and more than 88 cm (35 inches) in women according to International Diabetes Federation for Asian Population (IDF).


BMI Calculator table for adults

This is the World Health Organization's (WHO) recommended body weight based on BMI values for adults using BMI Calculator. It is used for both men and women, aged 20 or older.

Category BMI range - kg/m²
Severe Thinness < 16
Moderate Thinness 16 - 17
Mild Thinness 17 - 18.5
Normal 18.5 - 25
Overweight 25 - 30
Obese Class I 30 - 35
Obese Class II 35 - 40
Obese Class III > 40


BMI table for children age 2-20

The Centers for Disease Control and Prevention (CDC) recommends BMI categorization for children and teens between age of 2 and 20 using BMI Calculator.

Category BMI range - kg/m²
Underweight <5%
Healthy weight 5% - 85%
At the risk of overweight 85% - 95%
Overweight >95%


Ponderal Index

  • The Ponderal Index (PI) is similar to BMI in that it measures the leanness or corpulence of a person based on height and weight.
  • The main difference between the PI and BMI is the cubing rather than squaring of the height in the formula in the BMI Calculator (provided below).
  • While BMI can be a useful tool when considering large populations, it is not reliable for determining leanness or corpulence in individuals.
  • Although the PI suffers from similar considerations, the PI is more reliable for use with very tall or short individuals, while BMI tends to record uncharacteristically high or low body fat levels for those on the extreme ends of the height and weight spectrum.
  • Below is the equation for computing the PI of an individual using USC, again using a 5'10", 160-pound individual as an example:


BMI Calculator For Children

  • Your GP or health visitor can advise on where your child sits on the ‘centile charts’ used to estimate healthy weights for children using BMI Calculator.


BMI Calculator For Older people (over 65, possibly over 60)

  • Because muscle mass tends to drop and body fat tends to rise in older people, BMI may not be an accurate reflector of body fat if you're over 60 using the BMI Calculator.


BMI Calculator For Pregnant women

  • Usual BMI estimates do not apply if you’re pregnant using the BMI Calculator.


BMI Calculator If you are very muscular

  • BMI assumes you have an average amount of body fat, including ‘intra-abdominal fat’ – fat deep inside your stomach cavity rather than under your skin.
  • Intra-abdominal fat is much more closely linked to risks of type 2 diabetes and heart disease than fat under the skin due to less nutrition.
  • If you are very muscular, your level of body fat may be lower than predicted by your BMI using the BMI Calculator.
  • However, this only applies to people who do high levels of exercise – much more than average.


BMI Calculator If you are of Asian origin

  • People of Asian origin are prone to accumulating intra-abdominal fat (fat deep inside your stomach cavity rather than under your skin) at a lower BMI than people of Caucasian origin.
  • People with this pattern of weight gain are described as ‘apples’ rather than ‘pears’ from their body outline.
  • This means their health risks start to rise at a lower BMI because intra-abdominal fat is directly linked to the development of heart disease and type 2 diabetes.
  • The World Health Organisation has looked at the evidence and because of the variability between different Asian populations, it hasn't officially changed the cut-off points using BMI Calculator.
  • However, it does recommend that for public health purposes, some Asian groups should be considered overweight if their BMI is 22-25, and obese with a BMI of 26-31.


What is BMI (Body Mass Index) in Medical Terminology

  • BMI is a measurement of a person's leanness or corpulence based on height and weight and is intended to quantify tissue mass.
  • It is widely used as a general indicator of whether a person has a healthy body weight for their height using the BMI Calculator.
  • Specifically, the value obtained from the calculation of BMI is used to categorize whether a person is underweight, normal weight, overweight, or obese depending on what range the value falls between.
  • These ranges of BMI vary based on factors such as region and age and are sometimes further divided into subcategories such as severely underweight or very severely obese.
  • Being overweight or underweight can have significant health effects, so while BMI is an imperfect measure of healthy body weight, it is a useful indicator of whether any additional testing or action is required.
  • Refer to the table below to see the different categories based on BMI that are used by the BMI Calculator.


Alternative estimates of weight-related health risks

If you feel BMI may not accurately reflect whether you are overweight or obese, measuring your abdominal circumference, waist-hip, or waist-height ratio may give you a more realistic estimate in the BMI Calculator.


Why waist size also matters

  • Measuring your waist is a good way to check you're not carrying too much fat around your stomach, which can raise your risk of heart disease, type 2 diabetes, and stroke.
  • You can have a Healthy BMI Range and still have excess tummy fat, meaning you're still at risk of developing these conditions using the BMI Calculator.


To measure your waist:

  1. Find the bottom of your ribs and the top of your hips using the BMI Calculator.
  2. Wrap a tape measure around your waist midway between these points.
  3. Breathe out naturally before taking the measurement.


Regardless of your height or BMI, you should try to lose weight if your waist is:

  • 94cm (37ins) or more for men
  • 80cm (31.5ins) or more for women


You're at very high risk and should contact a GP if your waist is:

  • 102cm (40ins) or more for men
  • 88cm (34ins) or more for women


Waist circumference

You measure your waist circumference halfway between the bottom of your ribcage and the top of your hip bones, with the tape measure parallel to the floor.

You must be breathing out when you measure in BMI Calculator.



  • Increased health risk - ≥94cm
  • High health risk - ≥102cm



  • Increased health risk - ≥80cm
  • High health risk - ≥88cm


Waist to hip ratio

To check your waist to hip ratio, measure your waist circumference (as above), and your hip size at the widest part of your hips. Divide your abdominal circumference by your hip measurement to give a ratio in BMI Calculator.

  • In women, a waist to hip ratio greater than 0.85 is associated with greater than average risk.
  • In men, a waist to hip ratio greater than 1.00 is associated with greater than average risk.


Waist to height ratio

A recent study comparing BMI, waist circumference, waist to hip ratio and waist to height ratio found that the most accurate way of predicting your whole-body fat level was waist-height ratio.

Measure your waist circumference as above and simply divide it by your height – fairly obviously both measurements should either be in imperial (inches) or metric (cm).

Whole body obesity is defined by a waist-height ratio of:

  • 0.53 or more for men
  • 0.54 or more for women

Abdominal obesity was defined by a waist-height ratio of 0.59 or more in the BMI Calculator.


How to calculate BMI

  • If you want to calculate your BMI, you have to find out your weight and height first in BMI Calculator.
  • Once you know these values, you can arrive at the result by following the two steps mentioned below in BMI Calculator:
  1. Multiply your height by itself (height X height).
  2. Divide your weight by the answer you get in the first step.


The equations for calculating the BMI in BMI Calculator are as follows:


  1. International System of Units (SI)

    BMI = weight (kg) ÷ (height (m))²


    For a 177 cm (1.77 m) individual weighing 75 kg,

    BMI = 75 / (1.77 * 1.77) = 75/ 3.13 = 23.96

  2. Imperial System

    BMI = weight (lbs) ÷ (height (inches))² × 703


    For a 160-pound, 5’8” (68”) individual weighing 75 kg,

    BMI = (160/ 68*68) * 703 = (160/4624) * 703 = 24.3


Limitations of an Online BMI Calculator

  • Despite its popularity, BMI figures do have certain drawbacks when it comes to predicting future health issues.
  • Your BMI only uses your height and weight and does not consider your body composition.
  • So, the distribution of your muscle and bone mass might increase your BMI even if you’re very healthy and not likely to suffer from weight-related health issues in the near future.
  • Let’s take a closer look at the limitations of using BMI for various age groups using the BMI Calculator:



  • BMI is not considered accurate since it only measures excess body weight instead of excess body fat.
  • Use BMI Calculator For all your doubts.
  • So, it’s a good idea for adults to use BMI along with other measures to understand their future health risks.


The drawbacks of using the BMI Calculator for adults include:

  • Older adults will likely have more fat than younger individuals who have the same BMI.
  • Women are more likely to have more body fat than men who have an equivalent BMI.
  • Athletes and muscular people will probably have a higher BMI than others since they have large muscle mass.


Young Adults and Children

  • BMI cannot take into account a child’s growth rate and maturity.
  • Typically, BMI can be used to identify obese children, but not overweight children as a slightly higher BMI could be caused by increased fat-free mass.
  • Use BMI Calculator to track everything.
  • Despite the slight discrepancies, it’s possible to use BMI to accurately indicate the body fat of around 90% of the population.


What are the health risks related to being overweight?

Excess weight brings with it countless health complications, some of which can be fatal. A higher BMI than average (over 25) is associated with increased risks for diseases like:

  • Type 2 diabetes
  • Heart conditions
  • Higher levels of LDL cholesterol and lower count of HDL cholesterol in the blood, increase the chances of coronary artery diseases and heart attacks
  • High triglycerides
  • Stroke
  • High blood pressure
  • Gall bladder-related complications
  • Insulin resistance
  • Osteoarthritis or breakdown of joint cartilage leading to painful joints
  • Sleep apnea or intermittent breathing obstruction during sleep
  • Atherosclerosis or the building up of cholesterol deposits (plaques) in blood vessels (arteries)
  • Skin health problems like skin tags, darkening of the skin
  • Breathing trouble
  • Hernia
  • Varicose veins
  • Cataract
  • Gout
  • Stress incontinence or urge to urinate frequently
  • Certain types of cancer (breast, colon, endometrial, gall bladder, kidney, liver)
  • Clinical depression and other mental health issues
  • Polycystic ovarian disease in women leads to reduced fertility and other menstrual irregularities.


What are the risks of being underweight?

Having a BMI below 18.5 is also fraught with health risks, such as the ones listed below:

  • Vitamin deficiencies
  • Anemia (low red blood cell count and hence reduced capacity to carry oxygen)
  • Diminished immunity or the ability to ward off infections
  • Osteoporosis or brittle bones that break easily
  • Malnutrition
  • Developmental delays in children
  • Hormonal imbalances
  • Disruptions in women's menstrual cycle cause complications in conception
  • Less nutrition in your body weight



BMI Calculator helps to prevent obesity and know your healthy weight index value to keep your body in shape. Check More Medical Health Related Calculator on Drlogy Calculator to get exact health solution.



  • Body mass index by Wikipedia [1].
  • Calculate Your Body Mass Index [2].


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BMI Calculator FAQ

What is a BMI Calculator?

  • A BMI calculator is an online or offline device that measures your body mass index. 
  • The body mass index or BMI is a measure of how much body mass you have in relation to your height and weight.
  • Body mass refers not only to the fat within your body but also to muscles and bones. 
  • It is calculated by taking your weight and dividing it by the square of your height. 
  • The BMI figures let you know whether you are within the normal weight range, or if you are underweight or overweight.
  • Both high BMIs and low ones are known to raise a host of health problems, especially as you age. 
  • However, a high BMI in itself is not always, medically speaking, a cause for alarm. It should be viewed in conjunction with other health parameters.

How to calculate BMI?

  • To find out if your BMI is or someone else’s BMI, the calculation process is simple. 
  • You can do this yourself by using a handheld BMI Calculator or do this online via websites or apps containing body mass index calculators or BMI Calculator.
  • To arrive at the result yourself, you simply divide your weight in kilograms by the square of your height in meters. 
  • Or simply input your height and weight in an app or website and the BMI results will flash on your screen.

If the numbers show that your BMI is above normal or below the normal range, you should get yourself checked by a doctor at least once every six months or at least once a year.


  • A number between 18.5 to 25 kg/m2 is considered a normal BMI
  • Less than 15 is classified as very severely underweight
  • From 15 to 18 is categorized as underweight
  • From 25 to 30 is considered overweight. 
  • From 30 to 40 is classified as obese
  • Above 40 as very severely obese.

IS BMI Reliable?

  • Your BMI helps measure how appropriate your weight is for your height. 
  • While some people might be naturally broader, the BMI range allows for these discrepancies. 
  • The BMI measure works to help you understand whether you fall under the normal weight, overweight or obese category. 
  • People who carry extra weight, especially around their stomach, are prone to developing lifestyle diseases such as diabetes, cancer or heart issues. 
  • For adults, the BMI offers a good estimate of weight-related health problems.
  • Most often, physicians accurately measure your height and weight and use your BMI to understand your future health risks. 
  • If your BMI is higher than it should be, they will likely recommend some kind of diet and exercise regime to bring your weight down.
  • A body mass index in the low range signals that you could be malnourished. 
  • Maybe your body isn’t properly absorbing nutrients or maybe you’re just not getting enough calories to support your activity level.

How Do I calculate my BMI

  • BMI or body mass index is a measure of how much body mass an individual has according to his weight and height. 
  • To calculate your BMI, simply divide your weight in kilograms by your height squared in meters or use BMI Calculator. 
  • You can also find the results instantly by entering the height and weight data in online BMI calculators. 
  • BMI is not always an appropriate indicator of a person’s health. 
  • Growing children and elderly people may have less muscle mass and therefore lower weight, thus lowering their BMI in Calculator. 
  • On the other hand, athletes may have higher BMI as they put on plenty of muscle from exercise.








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