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Dr Harsh Shah - GI & HPB Oncosurgeon in Ahmeadbad
Dr Harsh Shah - GI & HPB Oncosurgeon in Ahmeadbad

BMI Calculator


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Your BMI is:

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Health Advice
BMI Weight Ranges
Less than 18.5 = Underweight
Between 18.5 - 24.9 = Healthy Weight (Normal)
Between 25 - 29.9 = Overweight
Over 30 = Obese

BMI Calculator | Body Mass Index

Want to know more about your body weight and its impact on your health? Understanding your Body Mass Index (BMI) can help you see if your weight is in a healthy range. The best part is, calculating your BMI is easy! With a BMI calculator, you can quickly see where you stand and what actions to take. Let’s explore this helpful tool that lets you make better choices for your health!
  • What is BMI?
⦿ BMI, or Body Mass Index, is a number calculated from your weight and height. It helps you see if your weight is healthy for your body type.
 
⦿ To calculate it, divide your weight in kilograms by your height in meters squared. This gives an idea of how much body fat you have compared to your size.
 
⦿ While BMI is useful, it doesn’t cover everything about health. Things like muscle, bone density, and where fat is stored also matter. So, BMI is just one part of understanding your overall health.
  • BMI Chart
Below is the BMI chart provides a detailed Body Mass Index (BMI) that visually represents BMI values based on a person’s height and weight.
BMI-Chart

What is a BMI Calculator?

⦿ A BMI Calculator is a tool used to calculate your body mass index. This simple formula helps you check if your weight is healthy for your height. It uses measurements like your weight in kilograms and height in meters.
 
⦿ The calculator gives quick results, showing your BMI in categories like underweight, normal weight, overweight, and obesity. It’s easy to use, available online or in apps.
 
⦿ Using this tool can be helpful for tracking your health over time. Many people use it to learn more about their well-being without needing complex medical tests.

Why Use a BMI Calculator?

⦿ Using a BMI calculator gives you a quick look at your health status. It’s a simple tool that only needs your height and weight to check if you’re in a healthy weight range. This ease of use makes it available to everyone.
 
⦿ Tracking changes over time is important for understanding your body. Regular BMI checks help spot trends, which can inspire healthier choices.
 
⦿ Knowing your BMI also helps when talking to healthcare providers about potential health risks or actions you might need to take. It’s more than just numbers—it’s about taking charge of your health and making smart decisions for your lifestyle.

How to Calculate BMI?

Calculating your BMI is simple and helps you understand if your weight falls within a healthy range. Follow these steps to determine your BMI accurately.
  • Gather your measurements
⦿ Weight in kilograms (kg): If you have your weight in pounds, convert it by dividing the number by 2.205.
 
⦿ Height in meters (m): If your height is in inches, convert it by dividing the number by 39.37.
  • Use the BMI formula
BMI = weight (kg) / (height (m))²
  • Example calculation
⦿ If you weigh 70 kg and are 1.75 m tall, the formula would be:
    • BMI = 70 / (1.75 × 1.75)
    • Result: BMI = 22.86

How to Use the BMI Calculator?

Using a BMI calculator is easy and fast.

⦿ Start by gathering your height and weight. Make sure to use the correct units—metric (kilograms and meters) or imperial (pounds and inches).

⦿ Then, enter your details into the calculator. Most online calculators have fields for both height and weight. After entering the information, click the calculate button.

⦿ Your BMI will appear along with an explanation of what it means. This can help you know if you’re in a healthy range or if lifestyle changes are needed based on your BMI result.

BMI Ranges

BMI is divided into five main categories to help determine if a person’s weight is healthy. These categories are based on the relationship between weight and height. The categories are:
  • Underweight
A BMI under 18.5 means a person is underweight and may need to gain weight for better health.
  • Normal weight
A BMI between 18.5 and 24.9 is considered healthy and reflects a good balance between height and weight.
  • Overweight
A BMI between 25 and 29.9 suggests excess weight, which may increase the risk of health problems.
  • Obesity
A BMI between 30 and 35 shows obesity, which raises the risk of conditions like heart disease and diabetes.
  • Severe obesity
A BMI above 35 is severe obesity, significantly increasing the risk of serious health issues.

BMI Table & Chart For Adults

This is the World Health Organization’s (WHO) guideline for healthy body weight, based on BMI values for adults. It applies to both men and women aged 20 and above.
Classification BMI Range (kg/m²)
Severe Thinness < 16
Moderate Thinness 16 - 17
Mild Thinness 17 - 18.5
Normal 18.5 - 25
Overweight 25 - 30
Obese Class I 30 - 35
Obese Class II 35 - 40
Obese Class III > 40
Here is a BMI chart for adults, showing the relationship between height (in meters) and weight (in kilograms). The chart categorizes different BMI ranges:
BMI chart for adults

BMI Table & Chart For Children and Teens

The Centers for Disease Control and Prevention (CDC) recommends using BMI categories to assess the weight of children and teens aged 2 to 20.
Category Percentile Range
Underweight < 5%
Healthy weight 5% - 85%
At risk of overweight 85% - 95%
Overweight > 95%
This is a BMI-for-age percentile chart for boys aged 2 to 20 years. It shows the 5th, 10th, 25th, 50th, 75th, 85th, 90th, and 95th percentiles. The chart helps you see how BMI typically changes as boys grow, with each curve representing a different percentile based on age.
BMI for age percentile chart for boys
This is a BMI-for-age percentile chart for girls aged 2 to 20 years. It shows the 5th, 10th, 25th, 50th, 75th, 85th, 90th, and 95th percentiles. The chart helps you understand how BMI changes as girls grow, with each curve representing a different percentile according to their age.
BMI for age percentile chart for girls

Health Risks Related to Being Overweight

Being overweight can significantly affect your overall health, increasing the risk of various health problems. Some common risks include: 
  • Heart disease
  • High blood pressure
  • Stroke
  • Type 2 diabetes
  • Sleep apnea and breathing difficulties
  • Joint pressure leading to osteoarthritis
  • Cancers like breast, colon, and endometrial
  • Fatty liver disease
  • Gallbladder disease
  • Hormonal imbalances impacting fertility and periods
  • Kidney disease
  • GERD (Gastroesophageal reflux disease)
  • Breathing issues and reduced lung function
  • Mental health problems such as anxiety and depression
  • Skin issues like infections and rashes

Health Risks Related to Being Underweight

Being underweight can also pose significant health challenges, often leading to deficiencies and other complications. Below are some of the most common health risks associated with being underweight.
  • Risk of malnutrition
  • Weak immune system and frequent infections
  • Osteoporosis and bone fractures due to low bone density
  • Anemia and iron deficiency
  • Fertility problems and irregular periods
  • Fatigue and low energy levels
  • Hair loss and brittle nails
  • Muscle weakness and reduced muscle mass
  • Vitamin deficiencies such as vitamin D and calcium
  • Delayed wound healing
  • Heart problems like low blood pressure and irregular heartbeat
  • Risk of hypothermia due to low body fat
  • Digestive issues like bloating and constipation
  • Mental health problems such as anxiety and depression
  • Complications during surgery or recovery

Tips for Maintaining Optimum Health

  • Follow a balanced diet with nutrient-rich foods like fruits, vegetables, lean proteins, and healthy fats.
  • Stay hydrated to keep your body functioning well.
  • Include regular exercise in your routine, aiming for at least 150 minutes of moderate activity each week.
  • Choose exercises you enjoy, such as walking or cycling, to stay consistent.
  • Manage stress with practices like meditation or yoga for better emotional health.
  • Get enough sleep to maintain energy and support cognitive function.

Limitations of BMI (Body Mass Index)

⦿ No distinction between muscle and fat: BMI doesn’t separate lean muscle from body fat, which can misclassify muscular individuals.

⦿ Ignores fat distribution: It doesn’t consider where fat is stored, missing health risks related to abdominal fat.

⦿ Not suitable for all populations: Its accuracy can vary for older adults, children, and different ethnic groups.

⦿ Excludes other health indicators: BMI doesn’t factor in important health aspects like blood pressure, cholesterol, or blood sugar.

⦿ No consideration for age and gender: It doesn’t adjust for natural differences in body composition based on age or gender.

What is the BMI formula?

⦿ The Body Mass Index (BMI) formula is simple and helps assess your weight in relation to your height. To calculate your BMI, divide your weight in kilograms by the square of your height in meters. The formula is: BMI = weight (kg) / (height (m))².
⦿ If you prefer using pounds and inches, the alternative formula involves multiplying your weight in pounds by 703 and then dividing by the square of your height in inches.
⦿ Either method quickly estimates whether you fall under the categories of underweight, normal weight, overweight, or obese.
 
Below are examples of how to calculate BMI using both units for a 6’0″, 180-pound individual.
Body Mass Index BMI formula
This calculation shows that a person who is 6’0″ and weighs 180 pounds has a BMI of 24.4, which falls within the normal weight range.

What is the BMI prime formula?

⦿ The BMI prime formula is a variation of the standard BMI calculation, offering a simpler way to assess weight in relation to height. This makes it easier for some people to understand their body composition.
 
⦿ It divides your BMI by 25, representing the upper limit of the normal weight range. The result shows how far you are from this healthy threshold.
 
⦿ For example, if your BMI is 30, dividing it by 25 gives a BMI prime of 1.2. This number can help guide weight management and health goals.
 
BMI prime is a dimensionless ratio of two BMI values. A BMI prime below 0.74 indicates underweight, 0.74 to 1 is normal, above 1 is overweight, and over 1.2 is classified as obese. The table below shows weight classifications based on BMI prime:
Classification BMI BMI Prime
Severe Thinness < 16 < 0.64
Moderate Thinness 16 - 17 0.64 - 0.68
Mild Thinness 17 - 18.5 0.68 - 0.74
Normal 18.5 - 25 0.74 - 1
Overweight 25 - 30 1 - 1.2
Obese Class I 30 - 35 1.2 - 1.4
Obese Class II 35 - 40 1.4 - 1.6
Obese Class III > 40 > 1.6

What is Ponderal Index?

⦿ The Ponderal Index (PI) is another measurement, similar to BMI, that helps assess body type based on height and weight. The main difference is that PI uses height cubed, unlike BMI, which uses height squared. While BMI works well for large groups, it may not accurately reflect an individual’s body composition, especially for people who are very tall or short.
 
⦿ PI is often more accurate for measuring leanness or body fat in these cases where BMI might give misleading results.
Ponderal Index PI
For example, for a person who is 6’0″ (72 inches) tall and weighs 180 lbs (81.65 kg), the Ponderal Index is 12.7. This provides an alternative way to assess body mass in relation to height.

Frequently Asked Questions

A BMI Calculator calculates your Body Mass Index using your weight and height. It helps you assess whether you're in a healthy weight range for your height.
To use a BMI calculator, simply input your weight and height. The calculator will give you your BMI, showing if you're underweight, normal weight, overweight, or obese.

BMI provides a general view of health, but it doesn’t account for muscle mass or fat distribution. It’s helpful as part of a wider health assessment.

A BMI of 25 means you’re classified as overweight, which may increase the risk of various health problems like heart disease and high blood pressure.

A BMI between 18.5 and 24.9 is considered healthy. This indicates that your weight is in a range that’s linked to better overall health and lower disease risks.

Yes, BMI is used for children, but it’s adjusted for age and gender. Percentiles help to determine if a child is underweight, normal weight, or overweight.

BMI helps assess if you're at a healthy weight for your height, which is crucial for reducing risks of chronic conditions like heart disease and diabetes.

BMI cannot determine your body fat percentage. It only provides a weight-to-height ratio and doesn’t account for muscle versus fat.

If you’re muscular, your BMI might place you in the overweight or obese category. This is because BMI doesn’t differentiate between muscle and fat.

While BMI can be used for older adults, it might not accurately reflect health due to muscle loss and fat gain with age. It’s important to use additional health measures.

Dr Harsh Shah Robotic Cancer Surgeon

Dr. Harsh Shah

MS, MCh (G I cancer Surgeon)

Dr Harsh Shah is a well known GI & HPB Robotic Cancer Surgeon in ahmedabad. He treats cancers of esophagus, stomach, liver, pancreas, colon, rectum & small intestines. He is available at Apollo Hospital.

5/5 - (13 reviews)

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