Body Mass Index (BMI) Calculator
Calculate your body mass index and determine your healthy weight range.
Understanding BMI and Related Metrics
Body Mass Index (BMI) is a measure used to estimate body fat based on a person's height and weight. It is commonly used to determine healthy weight ranges.
What is BMI?
BMI is a simple measure calculated by dividing a person's weight by the square of their height. It is used to assess general health status.
BMI = Weight (kg) / (Height (m))²
BMI does not directly measure body fat but is a useful tool for assessing general health risks.
BMI Categories
BMI values are divided into different weight categories:
- Underweight: BMI < 18.5
- Normal: BMI 18.5 - 24.9
- Overweight: BMI 25 - 29.9
- Obese: BMI ≥ 30
Ideal Weight Range
The ideal weight range represents the weight at which BMI falls between 18.5 and 24.9. This range is associated with the lowest risk of disease.
Ideal weight range can vary between individuals and depends on factors such as age, gender, muscle mass, and body frame.
Basal Metabolic Rate (BMR)
BMR is the minimum amount of energy your body needs to maintain basic life functions while at rest.
For Men: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age + 5 For Women: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age - 161
BMR forms the basis for determining your daily calorie needs and is adjusted according to your activity level.
Body Surface Area (BSA)
BSA is a measure used to calculate the total external surface area of the body. It is important in medical dosage calculations.
BSA (m²) = √(Height (cm) × Weight (kg) / 3600)
BSA is used in determining drug dosages and in some medical procedures.
Lean Body Mass (LBM)
LBM is the total weight of all tissues in the body excluding fat. It includes muscle mass, bones, organs, and water.
For Men: LBM = 0.407 × weight (kg) + 0.267 × height (cm) - 19.2 For Women: LBM = 0.252 × weight (kg) + 0.473 × height (cm) - 48.3
LBM is an important factor in assessing metabolic rate and physical performance.
Body Fat Percentage
Body fat percentage shows the portion of total body weight that is composed of fat tissue.
For Men: Body Fat % = (1.20 × BMI) + (0.23 × Age) - 16.2 For Women: Body Fat % = (1.20 × BMI) + (0.23 × Age) - 5.4
Body fat percentage can be a more accurate measure of health risks than BMI. However, this calculation method provides an estimate and is not as accurate as professional measurements.
Limitations of BMI
While BMI is a useful tool for general health assessment, it has some limitations:
- BMI cannot distinguish between muscle mass and fat mass. Athletes may have a high BMI but low body fat percentage. Therefore, BMI can be misleading for muscular individuals.
- BMI assessments may change with age. Different evaluation criteria may be used for older adults. As we age, muscle mass decreases and fat distribution changes, affecting BMI interpretation.
- BMI categories may vary for different ethnic groups. Health risks may appear at different BMI values for some groups. For example, Asian individuals may have increased health risks even at lower BMI values.
- BMI calculations are not valid during pregnancy and different evaluation criteria should be used. Weight gain during pregnancy is a natural process and BMI does not reflect health status during this period.