The body mass index or bmi calculator online is a ratio of mass to height. It is calculated as kg per square meter or pounds per square inch of height. Numeric BMI values correspond to weight categories including underweight, normal, overweight and obese.

BMI is used as an indicator of the relative 

Health & Wellness of a person. The Centers for Disease Control (CDC) and the World Health Organization (WHO) recognize that people who are overweight or underweight are at higher risk for certain health conditions. BMI also enables health professionals to discuss bodyweight objectively with their patients.

Calculator Use

The bmi online calculator finds the body mass index given weight and height. Calculate your BMI and find the BMI weight category for your height. The calculator also finds the normal weight range given your height.

Calculate BMI with weight in pounds, stones or kilograms. Enter height in inches, feet and inches, meters or centimeters.

BMI Formulas

Divide weight by height squared to find bmi calculator online. Note that you need to use kg and meters the standard units for the bmi calculator online formula are kg and meters. If you need other units of measure the calculator will convert among units for you.

In metric units, using kg and meters:

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BMI = weight ÷ height2

In metric units: BMI = weight (kg) ÷ height2 (meters)

In US units: BMI = weight (lb) ÷ height2 (inches) * 703

See additional bmi online calculator formulas below for accurate calculations in metric or imperial units.

How to Calculate bmi online calculator

Using metric units, where weight is in kilograms and height is in meters, divide weight by meters squared.

In US units, where weight is in pounds and height is in inches, divide weight by inches squared. Then multiply this figure by 703.

Example: Calculate BMI in metric units

Matilda weighs 64 kg and is 1.9 meters tall. What is her BMI?

Divide 64 by 1.92

BMI = w ÷ h2

BMI = 64 ÷ 1.92

BMI = 64 ÷ 3.61

BMI = 17.7

Normal Weight Range

Normal weight BMI is 18.5 to 24.9. To calculate your normal weight range use the following:

Metric units:

minimum weight (kg) = 18.5 × height2 (m)

maximum weight (kg) = 24.9 × height2 (m)

US units:

minimum weight (lb) = (18.5 ÷ 703) × height2 (in)

maximum weight (lb) = (24.9 ÷ 703) × height2 (in)

Body Mass Index bmi calculator online

Body mass index, or BMI, is one way to look at whether a person is at a healthy weight. BMI is a number based on height and weight. It can be used to place a person in categories ranging from underweight to obese.

But BMI doesn’t work well for everybody. There are other things to think about when deciding how much someone should weigh. If you have a BMI outside the normal range, your health care provider might also look at skinfold thickness (a measure of body fat), waist size, evaluations of your diet and family health problems, blood sugar levels, and other factors to find out if your weight might pose a health risk. To learn more about BMI and how extra body weight can affect your risk of cancer, see Body Weight and Cancer Risk.

Children's BMI

For children and young people aged between 2 to 18 years old, the BMI calculator takes into account age and gender as well as height and weight.

A child's BMI is given as a "centile". The centile number shows how their BMI compares with other children of the same age and sex as a percentage.

For example, a girl on the 75th centile is heavier than 75 out of 100 other girls her age.

The bmi online calculator works out if a child or young person is:

underweight – on the 2nd centile or below

a healthy weight – between the 2nd and 91st centiles

overweight – 91st centile or above

very overweight – 98th centile or above

See a GP if you're concerned about your child's weight. They may be able to refer you to your local healthy lifestyle programme for children, young people and families.

Limitations of the BMI

Muscle mass

The BMI calculation does not include muscle mass, which weighs more than fat.

Who can use the calculator

The BMI calculator is suitable for adults and children aged 2 years old and over.

The BMI calculator may not be suitable if you think you have an eating disorder or are being treated for one. Ask a GP for advice.

If you are pregnant, use your pre-pregnancy weight when calculating your BMI.

Summary

Bmi online calculator is a calculation used to estimate your body fat. Based on the bmi calculator online score, you may be categorized as being underweight, of normal weight, overweight, or having obesity. The BMI score may also be used to estimate your risk of certain diseases, like heart disease.

BMI has a number of limitations. It does not take into account your age, race, sex, fitness level, or muscle mass. As such, the same BMI can mean very different things in different people.

Multiple factors need to be considered when determining what a "healthy" body weight is. bmi calculator online is only one value of many and one that cannot be used on its own to diagnose any disease.