BMI Calculator
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BMI Weight Ranges
BMI Calculator | Body Mass Index
- What is BMI?
- BMI Chart

What is a BMI Calculator?
⦿ A BMI Calculator is a tool designed to assess an individual’s body mass index. This simple calculation helps determine if a person has a healthy weight for their height. It uses measurements like weight in kilograms and height in meters.
Why Use a BMI Calculator?
⦿ Using a BMI calculator provides a quick snapshot of your health status. It’s an easy tool that requires only your height and weight to assess whether you’re in a healthy range. This simplicity makes it accessible for everyone.
How to Calculate BMI?
- Gather your measurements
- Use the BMI formula
- Example calculation
• BMI = 70 / (1.75 × 1.75)
• Result: BMI = 22.86
How to Use the BMI Calculator?
⦿ First, gather your height and weight measurements. Ensure you use the appropriate units—either metric (kilograms and meters) or imperial (pounds and inches).
⦿ Next, input your data into the calculator. Most online calculators will have designated fields for both height and weight. After entering your information, hit the calculate button.
⦿ The result will display your Body Mass Index along with an interpretation of what it means for you. This can help determine if you’re in a healthy range or need to make lifestyle adjustments based on your BMI classification.
BMI Ranges
- Underweight
- Normal weight
- Overweight
- Obesity
- Severe obesity
BMI Table & Chart For Adults
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 |

BMI Table & Chart For Children and Teens
Category | Percentile Range |
---|---|
Underweight | < 5% |
Healthy weight | 5% - 85% |
At risk of overweight | 85% - 95% |
Overweight | > 95% |


Health Risks Related to Being Overweight
- Risk of heart disease
- Development of high blood pressure
- Possibility of stroke
- Likelihood of type 2 diabetes
- Sleep apnea and breathing problems
- Pressure on joints leading to osteoarthritis
- Development of certain cancers like breast, colon, and endometrial cancer
- Fatty liver disease
- Development of gallbladder disease
- Hormonal imbalances affecting fertility and menstrual cycles
- Risk of kidney disease
- Gastroesophageal reflux disease (GERD)
- Reduced lung function and breathing difficulties
- Mental health issues like anxiety and depression
- Skin conditions such as infections and rashes
Health Risks Related to 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 whole foods like fruits, vegetables, lean proteins, and healthy fats
- Stay hydrated to support overall bodily functions
- Include regular physical activity in your routine, aiming for at least 150 minutes of moderate exercise each week
- Choose enjoyable exercises, such as walking or cycling, to stay consistent
- Manage stress through techniques like meditation or yoga for better emotional health
- Prioritize getting sufficient sleep to maintain energy levels and support cognitive function
Limitations of BMI (Body Mass Index)
⦿ No distinction between muscle and fat: BMI doesn’t differentiate between lean muscle and body fat, leading to misclassification for muscular individuals.
⦿ Ignores fat distribution: It doesn’t account for where fat is stored, overlooking health risks related to abdominal fat.
⦿ Not suitable for all populations: Accuracy varies for older adults, children, and different ethnic groups.
⦿ Excludes other health indicators: BMI ignores important factors like blood pressure, cholesterol, and blood sugar.
⦿ No consideration for age and gender: Fails to adjust for natural differences in body composition due to age or gender.
What is the BMI Formula?
⦿ The Body Mass Index (BMI) formula is a straightforward calculation used to assess body weight relative to height. To find your BMI, you divide your weight in kilograms by the square of your height in meters. This means the formula looks like this: BMI = weight (kg) / (height (m))².
⦿ For those who prefer using pounds and inches, there’s an alternative version of the formula. Here, you multiply your weight in pounds by 703 and then divide that number by the square of your height in inches.
⦿ Using either method provides a quick estimate of whether you’re underweight, normal weight, overweight, or obese based on established BMI categories.
Below are examples of how to calculate BMI using both units for a 6’0″, 180-pound individual.

What is the BMI Prime Formula?
⦿ The BMI prime formula is a variation of the standard Body Mass Index calculation. It provides an alternative way to assess weight in relation to height, making it easier for some individuals to understand their body composition.
⦿ This formula divides a person’s BMI by 25, which represents the upper limit of the normal weight range. The result helps identify how far one might be from this healthy threshold.
⦿ For example, if your calculated BMI is 30, dividing that by 25 gives a BMI prime of 1.2. This number can help guide decisions about weight management and overall health goals.
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 a measure, similar to BMI, that helps assess a person’s body type based on their height and weight. The key difference is that the PI uses height cubed (instead of squared like BMI). While BMI is useful for large groups, it may not accurately reflect an individual’s body composition, especially for very tall or short people.
⦿ PI is generally better at measuring leanness or body fat in these cases, where BMI can sometimes give misleading results. Below is the formula used to calculate PI, using an example of a person who is 5’10” and weighs 160 pounds.

Frequently Asked Questions
What is a BMI Calculator?
How do I use a BMI Calculator?
Is BMI a reliable measure of health?
What does a BMI of 25 mean?
What is a healthy BMI range?
Can BMI be used for children?
Why is BMI important?
Can BMI determine body fat percentage?
What if I have a lot of muscle mass?
Can BMI be used for older adults?

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