BMI Calculator – Check Your Body Mass Index Instantly

Q: How do I calculate my BMI?

To calculate your BMI, use the formula: Metric: BMI = Weight (kg) / [Height (m)]² Imperial: BMI = [Weight (lbs) / Height (inches)²] × 703 You can also use our online BMI calculator for quick results.

Q: Why is my BMI 27 but I am not fat?

BMI only considers weight and height, not muscle mass or body composition. Athletes or muscular individuals may have a higher BMI but low body fat . In such cases, body fat percentage and waist-to-hip ratio give a better health assessment.

Q: What is the normal BMI?

A normal BMI ranges from 18.5 to 24.9 . This is considered a healthy weight and is associated with lower health risks.

Q: Is the BMI calculator correct?

BMI is a useful screening tool but not always accurate for individuals with high muscle mass, elderly people, or children . It does not differentiate between fat and muscle . For a better health analysis, consider body fat percentage and waist measurements .

Q: What is a woman’s BMI?

The BMI formula is the same for men and women . However, women naturally have a higher fat percentage than men. While BMI is useful, it should be considered alongside other health factors like body fat percentage and waist-hip ratio .

Q: What is BMI in kg?

BMI is calculated using kilograms (kg) for weight and meters (m) for height in the metric system: BMI = Weight (kg) / [Height (m)]²

Q: How accurate is BMI?

BMI is a simple measure for assessing weight categories but has limitations : It does not distinguish between fat and muscle . It may overestimate fat in muscular people. It may underestimate fat in older adults with lower muscle mass.

Q: Is BMI a good measure of health?

BMI is a general guideline but not a complete health indicator. Factors like body fat percentage, waist size, fitness level, and diet should also be considered for a complete health assessment.

Height:

Weight (kg):

What is a BMI Calculator?

A BMI calculator (Body Mass Index Calculator) is a tool that helps determine whether a person’s weight falls within a healthy range based on their height. The BMI index categorises individuals as underweight, normal weight, overweight, or obese. It is a commonly used health assessment tool worldwide.

How to Use the BMI Calculator?

Use our BMI Calculator to check your BMI range

Enter Your Weight:

Input your weight in kilograms (kg)

Enter Your Height:

Choose between: Centimeters (cm) and enter your height, or Feet & Inches and input both values.

Calculate BMI:

Click the “Calculate” button.

View Your Result:

Instantly see your BMI score and weight classification

BMI Chart & Healthy Weight Ranges

The National Institutes of Health (NIH) and the World Health Organization (WHO) classify BMI as follows (Weir & Jan, 2023):

Severely underweight	BMI < 16.5
Underweight	BMI < 18.5
Normal weight	18.5 – 24.9
Overweight	25 – 29.9
Obesity (Class I)	30 – 34.9
Obesity (Class II)	35 – 39.9
Obesity (Class III)	≥ 40 (severe/extreme obesity)

For Asian and South Asian populations, the points are adjusted due to higher health risks at lower BMI levels (Weir & Jan, 2023):

Overweight	23 – 24.9
Obese	≥ 25

Limitations of BMI

Does not distinguish between muscle and fat (misclassifies athletes).
May not accurately reflect health in elderly or pregnant populations.
In children, BMI percentiles (not absolute values) are used.

BMI Calculator for Men & Women

The BMI calculator male and BMI calculator female work the same way. However, body composition varies by gender. Men typically have more muscle mass, while women may have a higher fat percentage. The BMI chart female and BMI chart for men are identical, but additional health assessments are recommended for a more accurate evaluation.

BMI Formula – How is BMI Calculated?

The BMI formula is used globally to assess body weight in relation to height. The formula is:

Metric Formula:

\[ BMI = \frac{weight(kg)}{height(m)^2} \]

Imperial Formula:

\[ BMI = \frac{703 \times weight(lbs)}{height(in)^2} \]

What is BMI Prime?

BMI Prime is a simple way to understand how your weight compares to the upper limit of a healthy BMI, which is 25 kg/m² for most people. Instead of just looking at BMI, BMI Prime tells you how much above or below this limit you are. It is calculated using this formula:

\[ BMI Prime = \frac{BMI}{25} \]

Severely underweight	< 0.64
Underweight	0.64 – 0.74
Normal weight	0.74 – 1
Overweight	1 – 1.2
Obesity (Class I)	1.2- 1.4
Obesity (Class II)	1.4 – 1.6
Obesity (Class III)	> 1.6

Suppose a person has a BMI of 34 kg/m². Their BMI Prime would be:

34 ÷ 25 = 1.36

This means they are 36% above the healthy weight limit. If someone’s BMI Prime is 0.80, they are 20% below the upper limit, meaning they have a normal weight but are closer to being underweight.

What is Ponderal Index?

The Ponderal Index (PI) is a more refined alternative to the BMI calculator for assessing body composition. Unlike BMI, which sometimes misclassifies very tall or short individuals, the Ponderal Index formula considers height more accurately by cubing it instead of squaring. This makes it especially useful for people whose body proportions do not fit standard BMI classifications.

Metric Formula

\[ PI = \frac{Mass(kg)}{Height(m)^3} \]

Imperial Formula

\[ PI = \frac{Height(in)}{\sqrt[3]{Mass(lbs)}} \]

Understanding BMI and Its Role in Health

Maintaining a healthy weight is crucial for overall well-being. Health professionals assess weight-related health risks using three key indicators:

Body Mass Index (BMI)
BMI is a widely used method to determine if a person is underweight, healthy, overweight, or obese. It is calculated based on height and weight, providing a general estimate of body fat percentage. Higher BMI values indicate a greater risk of conditions such as heart disease, high blood pressure, diabetes, and certain cancers.

Limitations of BMI:

Overestimates fat in muscular individuals – Athletes or bodybuilders may have a high BMI but low body fat.

Underestimates fat in older adults – Muscle loss in elderly individuals can lead to misleading BMI values.
For a more accurate health assessment, BMI should be considered alongside other factors like waist circumference and overall lifestyle.

Waist Circumference and Health Risks
Waist size is a crucial factor in determining obesity-related risks. Excess fat around the abdomen increases the chances of developing heart disease and type 2 diabetes.

Healthy Waist Measurements:
Women: Below 35 inches (88 cm)
Men: Below 40 inches (102 cm)

To measure waist size correctly:
Stand straight and wrap a measuring tape around your waist, just above your hip bones.
Take the measurement after exhaling normally.
A larger waist circumference, even with a normal BMI, indicates a higher risk of health complications.

Obesity-Related Health Risks
Along with BMI and waist size, certain health conditions increase the likelihood of developing severe diseases.

Key Risk Factors:

High blood pressure (Hypertension)
High LDL cholesterol (Bad cholesterol)
Low HDL cholesterol (Good cholesterol)
High triglyceride levels
High blood sugar (Diabetes risk)
Family history of heart disease
Physical inactivity
Smoking

The Importance of Weight Management

For individuals with a BMI of 25 or higher and two or more risk factors, weight loss is highly recommended. Even a 5-10% reduction in weight can significantly lower the risk of obesity-related diseases.
If you are overweight but do not have additional risk factors, focus on maintaining your current weight and adopting a healthier lifestyle.

Frequently Asked Questions (FAQ)

How do I calculate my BMI?

To calculate your BMI, use the formula:

Metric: BMI = Weight (kg) / [Height (m)]²
Imperial: BMI = [Weight (lbs) / Height (inches)²] × 703

You can also use our online BMI calculator for quick results.

What is the BMI for 75 kg?

Your BMI depends on your height and weight. Use the formula:

Metric: BMI = Weight (kg) / [Height (m)]²
Imperial: BMI = [Weight (lbs) / Height (inches)²] × 703

You can also use our online BMI calculator for quick results.

Why is my BMI 27 but I am not fat?

BMI only considers weight and height, not muscle mass or body composition. Athletes or muscular individuals may have a higher BMI but low body fat. In such cases, body fat percentage and waist-to-hip ratio give a better health assessment.

What is the correct BMI for my age?

For adults, BMI classifications are the same regardless of age.

What is the normal BMI?

A normal BMI ranges from 18.5 to 24.9. This is considered a healthy weight and is associated with lower health risks.

Is the BMI calculator correct?

BMI is a useful screening tool but not always accurate for individuals with high muscle mass, elderly people, or children. It does not differentiate between fat and muscle. For a better health analysis, consider body fat percentage and waist measurements.

What is a woman’s BMI?

The BMI formula is the same for men and women. However, women naturally have a higher fat percentage than men. While BMI is useful, it should be considered alongside other health factors like body fat percentage and waist-hip ratio.

What is BMI in kg?

BMI is calculated using kilograms (kg) for weight and meters (m) for height in the metric system:
BMI = Weight (kg) / [Height (m)]²

How accurate is BMI?

BMI is a simple measure for assessing weight categories but has limitations:

It does not distinguish between fat and muscle.
It may overestimate fat in muscular people.
It may underestimate fat in older adults with lower muscle mass.

Is BMI a good measure of health?

BMI is a general guideline but not a complete health indicator. Factors like body fat percentage, waist size, fitness level, and diet should also be considered for a complete health assessment.

What is the Body Mass Index Formula?

The body mass index formula is calculated using weight and height. It helps in determining the body weight index calculator score for different individuals.