Weight Loss

How to Calculate Body Mass Index: Normal Range and Tips to Reduce BMI

Sumita Thomas

October 19, 2022

As the term suggests, Body Mass Index or BMI, serves as an indicator of one’s health or body weight. It is important to understand what exactly BMI means and how it can affect your health. Maintaining normal BMI ranges can prove to be the most basic step to maintaining good health.

In this article, we study in detail what BMI is, everything you need to know about BMI calculator, what your ideal BMI should be, how you can reduce your BMI and more.

Table of Contents

What is BMI?

Body Mass Index or BMI is a measurement of a person’s weight with respect to their height. In other words, it measures your body size by taking into consideration your weight as well as height.

By knowing your BMI ratio, you can determine if you have excess body fat for your height. BMI can generally serve as an indicator of your total body fat. However, this need not always be the case since a person with high muscle mass can fall in the overweight range as well.

Read More: BMI Calculator – An Informative Outlook on Body Mass Index (BMI)

The science behind BMI is that the taller a person is, the more tissue they have, which means they tend to weigh more than people who are shorter.

Most of the time, a person’s BMI correlates with their total body fat, which means that the higher your BMI score, the higher your total body fat. So, the results of a BMI calculator will tell you if you are in the normal range, or whether you are underweight, overweight or obese.

In this sense, your body mass index is more of an indicator of your health and body weight, rather than an actual measurement. If you find that you have a healthy weight in relation to your weight, that means that you are relatively healthy.

However, if you find that you are underweight, overweight or obese, that indicates that you may have mild to severe health complications due to excess body fat levels and it’s important that you work on getting your BMI to a normal range.

BMI Calculation Formula

Calculating body mass index is quite easy. You can use a BMI calculator that you can find online. All you have to do is enter your height, weight, age and sometimes, gender, and the BMI checker will give you the body mass index right away.

BMI can also be calculated using a mathematical formula. The formula involves dividing your weight in kilograms by the square of your height in metres. So, the formula for calculating BMI can be put as:

BMI = weight (kg)/square of the height (m2)

For example, if your weight is 68 kg and your height in metres is 1.65, then according to the formula, your BMI will be 24.98.

It is important to understand how one’s BMI can affect their health. Abnormal body mass index levels can negatively impact one’s. Therefore, care must be taken to ensure that you maintain your BMI within normal range.

Ideal BMI Range for Men and Women

For adults, the ideal range is between 18.5 and 22.9. If your BMI falls under these numbers, then you are considered to be healthy. For a more comprehensive understanding, here is the BMI classification for adults.

BMI Chart

1. BMI below 18.5 – Underweight

If your BMI is less than 18.5, then it means that you are underweight. To avoid health complications that may arise due to low levels of body fat, you need to put on more weight. Make sure you get in touch with your doctor or a dietician for professional insight and advice.

2. 18.5 to 22.9 – Healthy

If you have a BMI that falls in between 18.5 to 22.9, then it means that you have a healthy weight in relation to your height. This is your normal BMI range. When you maintain a healthy level of body fat, it means that you have a much lower risk of developing health complications.

3. 23.0 to 24.9 – Overweight

If you have a BMI that falls in between 23.0 to 24.9, it means that you are overweight. In other words, you have a higher than ideal level of body fats considering your height.

In such cases, it is important that you lose some amount of weight in order to improve your health. It is recommended that you talk to a doctor or dietician for professional advice.

4. 25.0 and above – Obese

If your BMI is more than 25.0, then it indicates that you are obese, or in other words, heavily overweight. It is far from your ideal BMI and it means that you have way too much body fat in relation to your height, and this can pose serious health risks.

It is important that you lose weight for health reasons. Make sure to contact your doctor or dietician for professional advice in such a situation.

Below 18.5Underweight
18.5-22.9Normal Range
25.0 and aboveObese

Ideal BMI Range for Children

When it comes to BMI checker for children, as well as teenagers, there are some slight differences as compared to an adult BMI calculator. In adults, body mass index is not related to their age or sex. No matter if you are male or female, the same BMI formula and same BMI chart applies to you.

However, in children and teenagers, the age and sex of the child need to be taken into consideration while calculating body mass index. This is because girls and boys who are still growing develop at different rates, so depending on how old they are, the amount of body fat they carry differs.

Put simply, children are not categorised by healthy weight ranges by doctors and health professionals mainly because of the following reasons –

  • Healthy weight ranges change as the height of the child increases
  • Male and female bodies develop at different rates
  • Healthy weight ranges change with each month of age when it comes to children

So, while calculating the body mass index for children and teenagers, doctors use the same formula that involves their weight and height. However, a major difference is that after they get the result of the BMI checker, they then locate the BMI as well as the age of the child on a BMI chart that is specifically made for kids, taking their age and sex into consideration too. This allows health professionals to determine if the child is in the normal BMI range.

How does BMI affect health?

As mentioned before, the body mass index is an indicator of your health. If your BMI is low and you are underweight, or if you have high BMI and you are either overweight or obese, these indicate that you are a high risk of bigger health complications.

For instance, if the BMI checker tells you that you have a BMI lower than 18.5, and you are underweight, it may mean that you are following a poor diet or you have adverse reactions to some medications.

If you have a BMI that is higher than the normal BMI range, that is, if you are overweight or obese, there is a very high chance that you may develop serious health conditions, if you haven’t already. If you have excess weight, then it means that your body has to work harder in order to function properly. Often, this puts too much pressure on the organs, which leads to the development of these health conditions.

Various studies have found strong correlations between being overweight or obese and developing serious health conditions. For example, those who are obese are more likely to suffer from chronic heart diseases, high blood pressure, diabetes, respiratory problems, osteoarthritis, stroke, some cancers, and other health complications. These diseases can often lead to premature death.

Apart from the physical effects of having an unhealthy BMI, there are psychological effects as well. Low BMI can prove to be an indicator of anorexia, which is an eating disorder where people are unnaturally obsessed with their weight and the food they consume. This can cause high levels of stress, anxiety and even depression.

On the higher end of the spectrum, we have people with high body mass index. These are the people who are overweight or obese. Being heavy can cause a body image issues, affecting your self-esteem and thereby causing, high levels of psychological stress. This is common in both children and adults.

If you have a body mass index that is lower or higher than the ideal BMI, then it is highly recommended that you get in touch with a doctor who can accurately analyse your condition and provide professional advice. This will help you attain a normal BMI range.

It is important to remember that you can work towards a healthier BMI by taking better care of your health.

Ways to reduce BMI

Today, there are many people who have a high BMI, which puts them at risk of various health complications. If you are among these people, then it is important that you work towards reducing your body mass index. This, in turn, will help one live a healthy life.

Below, we discuss some steps you can take in order to reduce your BMI and attain a healthy and normal BMI range.

1. Follow a healthy diet

Eating healthy and on time is extremely important if you wish to maintain a healthy weight. Make sure that your body receives all the nutrition it requires and cut down on junk food.

Consuming a lot of junk food is one of the easiest ways to gain weight and increase your BMI. Instead, eat healthy food like fruits and vegetables, as well as foods rich in fiber. These foods make you feel full for a longer time while also being extremely nutritious.

To ensure healthy eating, it is necessary to maintain a healthy balanced diet plan. You can find the best Indian diet plan for weight loss here.

2. Don’t skip breakfast and eat on time

Make sure that you do not skip breakfast. You will only feel hungry throughout the day and end up snacking a lot, mostly on unhealthy food.

Eating on time throughout the day is important if you want to have a healthy body mass index because it becomes easier to burn calories faster. Besides, you don’t feel tempted to binge on unhealthy foods in between meals.

3. Exercise regularly

Another key element in your journey of losing weight and reducing your BMI is regular exercise. Spend at least 30 minutes every day moving around, whether you are walking, jogging, running or working out.

In addition to helping you burn the calories that you need to, regular exercise also ensures you feel good, keeps you fit and active.

4. Make sure to drink plenty of water

The importance of drinking water cannot be stressed enough. Your body needs to stay hydrated at all times. Besides, many times, people confuse hunger with thirst. So, instead of drinking water, they end up eating and consuming lots of calories when a glass of water is what your body really needs.

5. Cut down your alcohol consumption

If you don’t want a beer belly, you need to cut down your alcohol consumption. Alcohol of any kind, not just beer, contains lots of calories. So, while trying to attain an ideal BMI, alcohol is not your best friend. In fact, a glass of wine contains as many calories as a chocolate piece.

While you try to reduce the number that the BMI calculator shows you, don’t forget that seeking help and advice from doctors, physicians and/or dietitians is very important. They will be able to give you a better understanding of your condition and help you get where you want to be.


Your body mass index gives you a clear idea of whether your body weight is ideal at your height or not.

Steps must be taken to ensure that you maintain normal BMI levels in order to stay healthy, and keep lifestyle disorders away. Follow the tips mentioned in this article to maintain your BMI at normal levels, and keep your health in check.

About the Author

For Sumita Thomas, good nutrition advice is less about what NOT to eat and all about HOW to eat. Armed with a master’s degree in clinical nutrition and dietetics from IGNOU, Sumita has worked with multi-specialty clinics and corporate clients, planning calorie-specific menus for their cafeterias. She’s also a certified diabetes educator, has worked in cardiac nutrition and is even a TUV-certified internal auditor for food safety management systems. Maybe that’s why she ensures her advice is always scientifically sound, which makes her a perfect fit for us at HealthifyMe. Of the belief that a healthy lifestyle can be achieved with the combination of a healthy mind, body and diet, Sumita recommends setting realistic goals – one health target a day – and gradually incorporating healthy ingredients to your daily diet. Does she practice what she preaches? For sure, and ensures all those around her do too. So get set, because that now includes you!

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