English 7 MIN READ 760 VIEWS June 4, 2023

BMI Calculator: All You Need to Know About it

BMI calculator

BMI or Body Mass Index is an important indicator of the body’s fat levels. A higher BMI means higher fat levels, which indicate a higher risk of diseases like type 2 diabetes, heart ailments, blood pressure, and certain cancers. Thus, a BMI test using BMI Calculator is an easy way for a BMI check.

A BMI calculator or a body mass index calculator is a tool used to calculate the body mass index (BMI). Height and weight are the two key parameters on which the results are dependent. Let’s understand more about the BMI formula and how to use it as an important health tool.

BMI Formula

Whether you are using a BMI calculator for women or a BMI calculator for men, the BMI formula remains the same. It is a useful tool for healthcare professionals and individuals who want to monitor their weight and assess their overall health status.

The BMI calculator formula uses the following mathematical equation: 

BMI = weight (kg) / (height (m))²
While the weight is in kilograms, the height is in metres. The formula divides the weight by the square of the height, giving you your BMI score. The score is then categorised as underweight, normal weight, overweight, or obese, based on standard ranges.

BMI Calculator : Calculate Your Body Mass Index




Height in centimeters:

weight in kilograms:

BMI Range 

Depending upon the BMI score derived using the BMI formula, the results are categorised under four heads:

  • Underweight
  • Normal Weight
  • Overweight
  • Obese

The standard BMI ranges referred to when using a BMI calculator female or a BMI calculator male are:

  • Underweight – BMI less than 18.5
  • Normal weight – BMI between 18.5 and 24.9
  • Overweight – BMI between 25 and 29.9
  • Obese – BMI of 30 or higher

BMI Chart for Adults

BMI for both men and women is calculated using the same BMI formula and they also follow the same BMI chart. However, women tend to have a higher percentage of body fat than men, even if they have the same BMI score. Therefore, other factors such as waist circumference and body composition are also considered when assessing an adult’s weight and health status.

BMI Chart for Children

BMI is also used in children to assess their weight and determine whether they are at a healthy weight for their age and height. The chart takes into account a child’s age, gender, height, and weight, and provides percentile rankings based on their BMI score. The percentile ranking indicates where the child falls in comparison to other children of the same age and gender.

The BMI categories for children are slightly different than those for BMI for women and BMI chart men. Also, they are based on age and gender-specific percentiles:

  • Underweight – BMI below the 5th percentile
  • Healthy weight – BMI between the 5th and 84th percentile
  • Overweight – BMI between the 85th and 94th percentile
  • Obese – BMI at or above the 95th percentile

Ideal BMI for Adults

The BMI chart men and women is the same. The ideal BMI for adults depends on several factors, including age, gender, and body composition. However, in general, a BMI between 18.5 and 24.9 is considered to be a healthy range for most adults.

Individuals with a BMI below 18.5 are considered to be underweight and may need to gain weight to reach a healthy range. A BMI between 25 and 29.9 indicates that an individual is overweight, and a BMI of 30 or higher indicates obesity, both of which may increase the risk for several health problems such as heart disease, diabetes, and high blood pressure.

Limitations of the BMI Calculator

While BMI is a useful tool for assessing weight and health status, it does have certain limitations. These are:

  • Ignores body composition factors – BMI only takes into account a person’s weight and height, and doesn’t differentiate between muscle mass, bone density, or body fat percentage. This means that individuals with a high muscle mass may have a higher BMI score even if they are not overweight or obese.
  • Inaccurate results for certain populations – BMI may not be an accurate measure of weight and health status for certain populations, such as athletes, pregnant women, and the elderly.
  • Does not identify fat storage location – The location of body fat is an important determinant of health risks. For instance, excess weight in the abdominal area increases the risk of heart disease and diabetes.
  • Not reflective of overall health status – BMI only provides information about weight status. It misses out on important factors like diet, physical activity, and genetics that impact health. 
  • Fails to account for ethnic differences – People of different ethnicities may have different body compositions and health risks, but the BMI chart gives out standard results. 
  • Not suitable for evaluating weight status in children and adolescents – BMI calculations for children and adolescents are based on age and gender-specific percentiles, but these percentiles do not reflect healthy weight status or body composition.
  • Fails to consider changes in body weight and health over time – BMI only provides a snapshot of an individual’s weight and health status at a given point in time. It doesn’t take into account changes in weight, muscle mass, or overall health over time.
  • Poor predictor of health outcomes for obese and underweight individuals – BMI score is not a good predictor of health outcomes for obese and underweight individuals. Some individuals in the same category may be at higher risk for health problems as compared to others.
ALT Text - BMI Calculator

How to Reach Ideal BMI?

Despite its limitations, it is important to keep BMI in check. A healthy BMI will cut down the risk of developing serious diseases that could lead to impaired quality of life and premature death. Reaching a healthy BMI requires a combination of healthy eating habits and regular physical activity. Here are some tips to reach your ideal BMI:

  • Follow A Balanced and Healthy Diet – Eating a diet that is rich in fruits, vegetables, whole grains, lean proteins, and healthy fats can help you maintain a healthy weight and reduce your risk for chronic diseases for both underweight and overweight individuals.
  • Watch Your Calorie Intake – Both underweight and overweight must be calorie-conscious. While underweight individuals must eat more than the recommended 2000 calories per day, overweight people must aim to reduce daily calorie intake by 500-1000 calories to reach their ideal BMI.
  • Stay Physically Active – Regular physical activity can help you maintain a healthy weight and reduce your risk for chronic diseases in people across all BMIs. Aim for at least 30 minutes of moderate-intensity exercise at least five times a week.
  • Monitor Your Weight – Regular monitoring of weight can help you stay on track and make adjustments to your diet and exercise routine as needed.
  • Seek Support – Reaching a healthy BMI can be challenging, so it’s important to seek support from friends, family, or a healthcare provider. Consider joining a support group, hiring a personal trainer, or consulting with a registered dietitian for guidance and support.

Health Risks of Being Overweight

Being overweight can pose several health risks and have negative implications for overall well-being. Here are some health risks associated with excess weight:

  • Cardiovascular Disease: Excess weight increases the risk of conditions such as heart disease, high blood pressure, and stroke.
  • Type 2 Diabetes: Obesity is a major risk factor for developing type 2 diabetes, a chronic condition that affects blood sugar regulation.
  • Joint Problems: The extra weight puts stress on joints, increasing the likelihood of conditions such as osteoarthritis, particularly in weight-bearing joints like the knees and hips.
  • Respiratory Issues: Obesity can lead to breathing difficulties, including sleep apnea and asthma, which can have a negative impact on overall lung function.
  • Certain Cancers: Obesity has been linked to an increased risk of various types of cancers, including breast, colon, and endometrial cancer.
  • Mental Health Concerns: Being overweight can contribute to low self-esteem, body image issues, and an increased risk of depression and anxiety.
  • Fatty Liver Disease: Excess weight can lead to the accumulation of fat in the liver, causing non-alcoholic fatty liver disease (NAFLD), which can progress to more severe conditions.
  • Reproductive Complications: Obesity can affect hormonal balance, leading to menstrual irregularities, infertility, and complications during pregnancy.

Health Risks of Being Underweight

Being underweight can have several health risks and adverse effects on overall well-being. Here are some risks associated with being underweight:

  • Nutritional Deficiencies: Insufficient body weight often indicates inadequate nutrient intake, leading to deficiencies in essential vitamins, minerals, and macronutrients. This can weaken the immune system, impair growth and development, and increase illness susceptibility.
  • Weakened Immune System: Underweight individuals may have a compromised immune system, making them more vulnerable to infections, illnesses, and slower disease recovery.
  • Osteoporosis and Bone Fractures: Inadequate body weight can contribute to decreased bone density and increase the risk of osteoporosis and fractures, especially in women.
  • Hormonal Imbalances: Insufficient body fat can disrupt hormonal balance, leading to irregular menstrual cycles and fertility issues in women. It can also impact hormone production and affect reproductive health in both men and women.
  • Muscle Wasting: Being underweight often means a loss of muscle mass, which can result in weakness, fatigue, and a decreased ability to perform physical activities.
  • Impaired Cognitive Function: Inadequate nutrition can affect brain health and cognitive function, leading to difficulties with concentration, memory, and overall cognitive performance.
  • Impaired Wound Healing: Underweight individuals may experience delayed wound healing due to compromised tissue repair mechanisms.
  • Increased Risk of Anemia: Insufficient intake of essential nutrients can contribute to anemia, resulting in fatigue, weakness, and impaired oxygen transport in the body.


Achieving and maintaining a healthy BMI is an important factor in overall health and well-being. A healthy BMI can help reduce the risk of chronic diseases such as diabetes, heart disease, and some forms of cancer.

While the BMI calculator is a useful tool for estimating a healthy weight range, it is important to keep in mind its limitations and to use it in conjunction with other measures such as waist circumference, body fat percentage, and overall health assessment. Making healthy lifestyle choices such as following a balanced diet, staying physically active, and seeking support from healthcare professionals can help you achieve and maintain a healthy BMI. 

Frequently Asked Questions About BMI Calculator

Log on to any online BMI calculator. Enter your height and weight in the BMI calculator. The result will show your BMI and its corresponding weight category.

The BMI calculator requires only two things to calculate BMI – weight in kg and height in metres. However, for interpretation of the BMI score one needs to know the age and the gender of the individual.

To calculate BMI, divide the weight in kilograms by the height in metres squared. Alternatively, use an online BMI calculator. Enter the values for height and weight in the BMI calculator. The result will show the BMI and its corresponding weight category.

The BMI of a person who weighs 70 kg will depend on their height. One can use a BMI calculator or BMI formula to determine their BMI.

The best BMI for adults is a BMI score between 18.5-24.9. It is regarded as normal weight.

20 BMI is a healthy BMI score. However, factors such as age, gender, body composition, and overall health status must be kept in mind to evaluate overall health.

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