BMI calculation and formula for BMI, works for men, women and children

BMI calculation and formula for BMI, works for men, women and children

Want to know how to calculate your BMI? Finding your body mass index is one of the easiest ways to predict your future health, as well as to keep tabs on your current health and fitness levels.

Some people are confused by body mass index. Maybe this is you. Maybe you don’t know how to calculate your BMI, or how to interpret the numbers once you do calculate it. If so, don’t worry! This guide to BMI calculation and the formula for BMI works for everyone – men, women and children.

And it’s easy to do! You can calculate your own BMI in just a few steps! In this article, you’ll learn:

  • How to calculate your BMI
  • What your BMI means for your health
  • The difference in BMI between men, women and children

Ready to try it? Let’s dive in! 

BMI Calculation: The Formula

First things first – how do you calculate your BMI? Well, first you’ll need your height and your weight. Calculating your BMI is much simpler if you can get your height in meters and your weight in kilograms. However, if you can’t, we’ll show you how to convert inches and pounds in just a few minutes

Here’s the formula for BMI:

It’s just your weight in kilograms, divided by your height in meters, then divided by your height in meters again.

If you want, you can also do it this way:

Take your height in meters and multiply it by itself. Then, divide that number into your weight in kilograms.

Easy, right?

Now, say you have your height in inches and your weight in pounds. That adds a little more math, but it’s still possible. To convert your height in inches to your height in meters, here’s what you do:

Multiply the number of inches by .0254

Then, get your weight in kilograms:

Multiply the number of pounds by .4535

As you can see, it really is easier to just start with your weight and height using the metric system.

Now you’ve got your measurements. What’s next?

Check your measurements and do the calculation

You now know the formula for BMI. You’ll need to find your height and your weight, though, so let’s start there.

When you take your height, you shouldn’t be wearing shoes. It’s also very helpful to have someone help to measure you, as your measurements will be more accurate that way.

Stand with your heels against the wall, and with your shoulders and your bottom touching the wall, too. Your back should be straight, and your feet flat on the floor. Using a pencil, have your friend mark your height onto the wall above you. This height should be measured at the crown, or the highest point, of your head.

With a tape measure, use the “centimeters” side to measure from the floor to the mark on the wall.

Your weight is easier. You may choose to visit a doctors office with an accurate, digital scale. Some “minute clinics” will let you step in and measure your weight, or sometimes you can find a digital scale at pharmacies as a courtesy to customers.

No matter where you weigh yourself, don’t forget that your measurements should be metric. If there’s a possible setting on the scale, change that to metric before you step on. Otherwise, simply convert your weight after the fact.

Write your measurements down, then calculate your BMI. Its as simple as that!

The formula is the same for men, women and children

No matter who you are, the way you’ll calculate your BMI is the same. It’s just kilograms divided by meters, divided by meters again.

The formula is the same for men, women and children, but the way you interpret the information will be different, depending on who you are.

If you’re a man or a woman over the age of 65, it’s usually a good idea to address BMI with your doctor. Recent studies have shown that BMI in older adults is naturally higher because of the way our bodies use fat as we age.

BMI is also used differently in children. We’ll look a little more closely at that in the next section.

Take the BMI calculation to the BMI chart

If you’re between the ages of 20 and 64, you’ll use a very straightforward method of interpreting your BMI. Here’s how it looks:

If your BMI is lower than 18.5, you’re underweight, and this could mean potential health risks.

If your BMI is between 18.5 and 24.9, you’re in a healthy range for BMI! Remember, this is true whether you’re a man or a woman.

If your BMI is between 25 and 29.9, you’re considered overweight.

If it falls between 30 and 39.9, medical professionals will consider you to be obese.

Finally, if your BMI is over 40, you’re considered morbidly obese and medical attention is recommended.

Kids are measured differently. Children grow at different rates, experiencing growth spurts and lags. It’s for that reason that a child’s BMI is measured on a percentile graph. If you have any concerns about your child’s BMI, it’s a good idea to talk to his or her doctor. Together you can rule out any health problems or even lifestyle issues which may cause your child to be an unhealthy weight.

Kids’ BMI is measured in the following way:

If your child’s BMI falls below the 5th percentile, he may be underweight. While this isn’t usually a huge problem, it could indicate developmental problems as well as malnutrition.

If your child’s BMI is between the 5th and the 85th percentile, you’re doing just fine! Your child is considered to be a healthy weight for his height and age.

If your child’s BMI is above the 85th percentile, he’s considered overweight. Kids who are overweight are at a greater risk for health problems, both now and in their adult lives.

What does it mean if you have a high BMI?

If you or your child has a BMI that’s considered to be underweight, you have a few possible side effects to consider. First, osteoporosis is more common in children and adults who have a low BMI, or who are underweight.

Secondly, anemia and malnutrition are a possibility in those who are underweight. Lacking essential nutrients, you’re more prone to health problems like these, and a chat with a dietician or your doctor is recommended.

If you or your child are considered overweight, there are many possible implications. People who are overweight are at a higher risk for cancer. They’re more likely to suffer heart conditions, heart attack, stroke and other complications. People who are overweight or obese are more likely to develop Type 2 diabetes – even children.

Those who have a higher than healthy BMI also may be at an increased risk of depression and suicide. This is not only true for adults, but for children, too. Obesity is a very cyclical thing – in many instances, the more overweight a person becomes, the more likely he is to feel depressed. This can lead to “vices” such as overeating that only serve to perpetuate the problem.

In addition to the immediate, dangerous risks of obesity like heart attack and stroke, there are other complications associated with being overweight. Joint pain, arthritis and bursitis are common among those who are overweight. High cholesterol, high blood pressure and high blood sugar are also risks.

Finally, women and men may both experience fertility problems if they are either underweight or overweight. Women who aren’t within a healthy BMI range before they become pregnant are more likely to experience pregnancy complications.

What are the benefits of a healthy BMI?

A healthy BMI doesn’t mean that you won’t ever be diagnosed with disease. You can be within a healthy weight range and still suffer from heart conditions, cancer, stroke or even Type 2 diabetes. However, being within a healthy weight range does carry benefits.

People who are of a normal weight are more likely to be active. This, in turn means they’ll sleep better, have more energy and have more self-confidence than their overweight counterparts.

Again, healthy BMI doesn’t mean you’ll never be diagnosed with a disease, but if you’re a healthy weight you’re proven to be less likely to suffer those diseases which affect overweight and obese people.

Women and men who are within a healthy BMI range are more readily able to have children. And women who are in a healthy weight range are more likely to have healthy pregnancies and healthy babies.

Of course, children who are in a healthy BM range are healthier, too. Kids who have good habits now are more likely to continue them later in life, meaning less risk for disease and an overall healthier lifestyle.

How do I keep my BMI in a healthy range?

Keeping your body mass index within a healthy range may be easy, or it may require a bit of willpower. If you’re currently overweight or obese, talk to your doctor about changing some lifestyle habits and starting to lose weight. If you’re morbidly obese, and your BMI is over 40, you may qualify for bariatric surgery. Bear in mind that surgery carries its own risks, and shouldn’t be taken lightly.

To keep your BMI within a healthy range, start by eating well. Incorporate fiber into your diet; fiber helps you feel full and also helps to “brush” toxins and waste from your body. Foods like broccoli and whole grains contain plenty of fiber – there’s usually no need for a supplement.

Be sure you drink plenty of water! This may sound like very basic advice, but there are many benefits to water. First, drinking a full glass of water before a meal will help you to feel full, reducing the chance that you’ll overeat. Water is also a diuretic, and will help flush fluids and toxins from your body. Water aids in the digestive system, helping your body metabolize the foods that you eat.

Get exercise. It’s recommended that you get 150 minutes of exercise each week. That may sound like a lot, but it’s really only 30 minutes, five times each week. Walking counts, and so does biking, walking your dog and even some gardening can count as exercise!

Get plenty of sleep. Sleep is critical to weight loss and metabolism, and getting any less than seven to eight hours of sleep can decrease your weight loss by as much as 55%!

Helping kids achieve a healthy BMI

As mentioned, kids grow in different ways, and at different rates. A ten year old boy could weigh 95 pounds or 75 pounds and still be classified in a healthy weight range for his height. But it’s important that caregivers and parents encourage a healthy lifestyle in kids, as BMI is equally important to their health.

Limit the screen time that kids have access to. Watching television or playing video games, obviously, won’t contribute to a healthy BMI in the same way that riding a bike or playing baseball will. If all else fails, get a dog. Pay your kid a few bucks weekly to walk the dog every day.

It’s also important that you limit the amount of processed, sugary foods and junk food in the house. While your kids may still have access to these foods at friends’ houses or at school, the fewer temptations there are at home, the better.

Portion control plays a big part in helping kids to maintain a healthy BMI. Talk to your doctor about what is considered an appropriate portion size for your child, and serve him that. Don’t punish your child with food, either. For instance, some parents have a rule that a child must clean his or her plate at mealtime. If your child isn’t hungry, don’t force him to eat!

Parents and caretakes play a vital role in the health and the BMI of their kids. Even the most simple steps, like taking a walk as a family, can go a long way toward lifelong habits.

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