BMI Calculator

Online BMI calculator to calculate your BMI in metric and US/UK units.


BMI Calculator

BMI is a simple mathematical formula, to measure the body fatness based on height and weight. You should be aware of your BMI because of the health risks of being overweight (25.0+ BMI). On the other hand, being too thin and having a BMI below the healthy range (18.5 to 24.9) can also be a health concern. Here’s free BMI calculator to help you stay on top of your body mass index. Calculate your BMI and find out if your BMI is within normal range.

How to use BMI Calculator

That’s it.

BMI Formula

BMI = 703 x Weight(lbs) / Height2(in2).

For example, if an adult weighs 190 pounds and is 5 feet 10 inches tall, he has a BMI of 27.

How did we do it? First, convert his height to inches only. 5 feet 10 inches is 70 inches. Multiply 70 times 70, which equals 4900. Divide his weight in pounds, 190, by 4900 which equals 0.039. Multiply 0.039 by 703 which equals 26.714 (which we round up to 27).

The BMI formula is pretty easy to calculate (and even memorize!) once you try it a few times.

Calculating your BMI is very simple, here’s BMI calculation formula for English and metric units:

English BMI Formula

BMI = ( Weight in Pounds / ( Height in inches x Height in inches ) ) x 703

Metric BMI Formula

BMI = ( Weight in Kilograms / ( Height in Meters x Height in Meters ) )

Calculating BMI with formula is pretty simple, divide weight (in pounds) by height (in inches), then multiply the result by 703.

What Does the BMI Result Mean?

Ideal BMI is considered between 18.5 and 25. If you have a BMI lower than 18.5, you are considered by the BMI calculation to be underweight. Anything over 25 is considered overweight, anything over 30 is considered obese, and over 40 is considered morbidly obese.

Things to Consider:

Although BMI can be used to measure body mass index for men, women and children, it does have some limits:

How to Calculate BMI

BMI is calculated the same way for both adults and children. The calculation is based on the following formulas:

U.S. Units – Pounds and inches:

Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703.

BMI = 703 x Weight(lbs) / Height2(in2)

Example: If weight = 150 lbs, Height = 5’5″ (65″)

Calculation: [150 ÷ (65)2] x 703 = 24.96

Metric – Kilograms and meters:

With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, divide height in centimeters by 100 to obtain height in meters.

BMI = Weight(kg) / Height2(m2)

Example: Weight = 68 kg, Height = 165 cm (1.65 m)

Calculation: 68 ÷ (1.65)2 = 24.98

Understanding the BMI Scale

You’ve always felt a little overweight and the number on the scale isn’t really a friendly one. Your doctor might be telling you that is would be good for you to lose a little weight. Though your weight is usually tracked by your doctor, another important number that is focused on is your BMI, or your body mass index. Calculated from your height, weight, and gender for people who are under 20 years of age, your BMI scale is more of a screening tool of how much or how little weight you are actually carrying than an actual diagnosis. What BMI is considered normal? When are you considered to be obese?

BMI Values for Adults

According to the WHO, the following table shows BMI values for adults (men and women, age 18 or older)

BMI Values for Men and Women:

CategoryBMI range – kg/m2
Very severely underweight< 15
Severely underweight15 – 16
Underweight16 – 18.5
Normal (healthy weight)18.5 – 25
Overweight25 – 30
Obese Class I (Moderately obese)30 – 35
Obese Class II (Severely obese)35 – 40
Obese Class III (Morbid)> 40

BMI Values for Children and Teens

According to the Center for Disease Control and Prevention (CDC), the following table shows BMI values for children and teens with ages 2-20 years. The above BMI calculator is perfect to calculate BMI for men, women, children and teens.

BMI Values for Children and Teens with ages between 2-20:

CategoryPercentile (%) Range
Underweight< 5%
Healthy weight5% – 85%
At risk of overweight85% – 95%
Overweight> 95%

BMI Between 18.5 – 24.9 Is Considered Normal

According to the Centers for Disease Control, a BMI that falls between 18.5 to 24.9 is a BMI that is considered to be healthy and normal. To get to your specific BMI number, you must divide your weight in pounds by height in inches, then square that number, and then that squared number is multiplied by a conversion factor of 703. Though this is a reliable screening tool there are some considerations that must be considered, such as the fact that most women will have more fat than men at the same BMI level.

BMI Between 25 – 29.9 Is Considered To Be Overweight

If your BMI is calculated to be between 25 – 29.9, you’re considered to be “Overweight” according to the CDC standardized charts. There are instances where people will end up falling into this category because they have spent time training to build up their muscular levels. Because muscle tissue weighs more than fat tissue, this can sometimes skew BMI results. It is important to keep in mind, however, that weight is just one risk factor when it comes to the development of disease.

BMI Over 30 Is Considered To Be Obese

For individuals who have a BMI over 30, a vast majority of them will have some form of excess fat buildup, even if they are training or exercising on a daily basis. By keeping your BMI levels down, you can reduce your risks of developing future health issues, such as:

Are You Concerned About Your BMI?

If you are concerned about your BMI, then have a discussion with your doctor about the things you might be able to do to reduce your overall weight. Common strategies include behavioral change programs through counseling, diet and nutritional education and change, increased exercise, and prescription medications that can help people to lose weight. Some people choose for optional surgeries as well. The American Medical Association has just classified obesity as a disease – you can get help. You can work to lower your BMI. By knowing what these numbers mean, you are taking the first step toward creating a healthier you.

Body Mass Index (BMI) FAQ

What is BMI?

BMI, or Body Mass Index, is just one part of your overall health picture. Other risk factors such as blood pressure, exercise, cholesterol level, etc. can impact your health as well.

If you are overweight, even a small amount of weight loss could help to lower your risk of disease. If your BMI is not normal, you should talk to your physician or health care provider.

What does my BMI number mean?

A BMI between 18.5 – 24.9 Is considered normal, 25 – 29.9 is overweight and anything over 30 is considered to be obese.

Is BMI calculated differently for children?

Yes. Calculating Body Mass Index (BMI) in teenagers and children requires gender-specific and age-specific growth charts. You should discuss any concerns you may have about your child’s weight or other nutritional problem with their pediatrician or your family physician.

How is BMI and my health related?

Body Mass Index is not a test or diagnostic for a particular condition. An abnormal BMI can, however, be a risk factor for other conditions including heart disease.

If your BMI is not normal, you should consult your physician about other steps to take to improve your overall health. Your physician may recommend changes to your diet, increased exercise, and better nutrition.

Keep in mind that BMI does not measure body fat. It is entirely possible that a bodybuilder could have the same BMI as an obese person. This is because BMI is calculated only by height and weight and doesn’t take other factors into consideration.

Last Updated on June 12, 2024