BMI Calculator for men, women, kids, Calculate your BMI directly

You’ve been hearing a lot about BMI, or body mass index, lately. But you may not be sure how to find yours. Well, finding your body mass index is easy – it’s just a simply calculation. But did you know that:

  • Adults and kids use a different BMI calculator?
  • Your waistline may affect your BMI?
  • Men and women use the same BMI calculator?

Let’s talk about how to calculate your BMI, and about what the number means for you and your health.

A BMI Calculator for Everybody

Wouldn’t it be so easy if there were a BMI calculator for everybody? If just one simple formula could predict your risk of disease and your overall health? What if a simple math equation could tell you if you were over- or underweight?

There is, and it can! Calculating your BMI is very easy to do, and it can tell you a great deal about your health.


  • Men and women with a BMI higher than the normal range are at a greater risk of developing adult onset diabetes.
  • Lowering your BMI can actually help reduce that risk.
  • Men and women with a BMI lower than the normal range are likely to become anemic.
  • Women with a BMI lower than the healthy range may begin to experience problems with menstruation.
  • Men with a BMI outside the healthy range may experience fertility problems.

So you see, your BMI can tell a lot about not just your weight, but your health as a whole. And it’s so easy to calculate, whether you’re a man or a woman.

How Do I Calculate My BMI?

You need two pieces of information in order to calculate your body mass index. You’ll need to know your height in meters and you’ll also need to know your weight in kilograms.

If you live in a country which uses metric measurements, you’re all set. But if you’re in a country that uses the standard system, you’ll need to convert those figures.

Take your weight in pounds and convert it to kilograms. Then, take your height in inches and convert it to meters. So, for example, a 5 foot tall woman who weighs 130 pounds would, instead, use 1.524 meters and 58.97 kilograms.

Now, it’s time to pull out your calculator. Alternatively, there are BMI calculators available online. Just take your weight and divide it by your height (in kg and m). Then, take the answer you got and divide it by your height in meters again.

That’s your BMI. So that five foot tall woman we mentioned has a body mass index of 25.39.

And that’s it! That’s all there is to calculating your BMI.

Is There a BMI Calculator for Kids?

First, let’s define “kid.” The CDC defines a child as everyone between the ages of 2 and 19. Most children within this age range are still seeing a pediatrician, and that doctor will

Kids’ BMI is calculated a little differently than an adult’s is. Of course, height and weight are used in the calculation of a child’s BMI. But when you determine a kid’s BMI, you’ll also factor in sex and age.

The easiest way to calculate a child’s BMI is just to visit an online calculator, or to visit the doctor’s office. You’ll plug in your child’s height, weight, birthday, sex and the date you measured her. Using those numbers, the BMI is calculated.

Once those numbers are figured up, the BMI is compared against kids of the same age as your child. The result? A percentile.

Percentile ranges are how kids’ BMI ranges are determined. If your child is:

  • Between the 5th and 85th percentile, his BMI is considered normal.
  • Less than the 5th percentile, your child may be underweight.
  • Between the 85th to the 95th percentile, your child is probably overweight.
  • Over the 95th percentile, your child is considered obese and should visit the pediatrician.

So, while BMI is calculated similarly for kids as it is for adults, the range of healthy BMI is figured out just a little differently.

Does a Calculator Differ for Men and Women?

When you were a kid, the healthy range of your BMI was different than it is now. However, at the age of around 20, it all evens out! That said, there’s no different calculator for men than there is for women.

Whether you’re a man or a woman, and whether you’re 25 or 55 years old, your body mass index will be calculated in exactly the same way. And, just as for kids, there are healthy and unhealthy ranges for your body mass index.

If your BMI is less than 18.5, you’re probably underweight. This doesn’t always signify bad health. But it does mean that you could be at a greater risk of complications like a lack of nutrients, or even digestive trouble.

If your BMI comes out to anywhere between 18.5 and 24.9, you’re considered to be of a healthy weight. You’re at an average risk for diseases like heart disease, anemia and more.

If your BMI is high, between 25 and 29.9, you’re considered overweight. That means you may be more likely to get diabetes, to suffer from stroke, heart attack or other heart condition, and you may even be at a higher risk for cancer.

Finally, if your BMI is 30 or higher, please speak with a doctor. You’re considered obese, which carries huge risks to your health. Some of those risks are fatal.

So does a calculator differ for men and women? Nope! No matter who you are, your BMI is calculated in exactly the same way, past the age of 20.

Can BMI Calculate My Waistline?

Your BMI can’t determine your waistline. But, your waistline may play a big part in how your BMI is interpreted!

Recently, doctors and scientists have figured out how to factor your waist measurement into your BMI. As it would turn out, the places on your body where you carry your weight can actually impact your likelihood to get diseases. Put simply, extra fat around the middle means big trouble for your kidneys, heart, pancreas, liver and more.

So, doctors will sometimes now incorporate waist measurements into BMI with an additional measurement, the waist to height ratio. And, like your BMI, your waist to height ratio should fall within a healthy range.

To find your waist to height ratio, simply divide the circumference of your waist (in centimeters) by your height (also in centimeters). Then, take your answer and multiply it by 100.

If you’re in a healthy range, your waist to height ratio (WHtR) will fall somewhere between .3 and .5. If your WHtR is over .5, you should consider lifestyle changes, as you’re at a greater risk for disease.

Again, these measurements are only applicable to adults, Children should not rely on this chart. Obviously, pregnant women shouldn’t either.

Your BMI Calculations

So, you’ve calculated your BMI using the simple formula:

Body weight in kilograms divided by height in meters, divided by height in meters again.

What now? What should you do with this information? Well, if your BMI is in an overweight or obese range, the first thing you’ll want to do is chat with your doctor. Together, you and your doctor will determine what factors may be influencing your body mass index. Those factors could range from something like your diet even to something as simple as muscle mass.

If your BMI is in the normal range, there’s not much you need to do. Take a look at your lifestyle. Ensure that you’re eating a healthy, well-balanced diet, and that you’re getting the recommended amount of exercise. The Centers for Disease Control recommend that adults get about 2 and a half hours each week of aerobic activity, plus some strength training, too.

If you’re considered underweight, you may want to talk to your doctor anyway. You and your physician can determine whether you need to increase your exercise, your caloric intake or make other lifestyle changes. He may even recommend that you take an iron supplement or multivitamin, as vitamin deficiency is common in those who are underweight.

Is your BMI a perfect predictor of disease? Of course not. But does it do a fair job of determining if you’re at risk? Yes! Very much so! Whether you’re a man or a woman, tracking your BMI can assist you in ensuring that you’re healthy, and that you remain that way!