1. What are BMI and BSA?

BMI (Body Mass Index) is a measure of body fat based on height and weight. BSA (Body Surface Area) estimates the total surface area of the human body. Both are widely used in clinical practice for assessment and treatment planning.

2. How the Calculations Work

The calculator uses these formulas:

Where:

• Weight — Measured in kilograms (kg)
• Height — For BMI: meters (m), for BSA: centimeters (cm)

Note: The BSA formula shown is the Mosteller formula, one of the most commonly used BSA calculation methods.

3. Clinical Importance

BMI: Used to classify underweight, normal weight, overweight and obesity. Helps assess risk for weight-related health problems.

BSA: Used in medical practice to calculate drug dosages, chemotherapy regimens, and to index various physiological measurements.

4. Using the Calculator

Instructions: Enter weight in kilograms and height in centimeters. The calculator will automatically convert height to meters for BMI calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a normal BMI range?
A: 18.5-24.9 kg/m² is considered normal. Below 18.5 is underweight, 25-29.9 overweight, and 30+ obese.

Q2: Why are there different BSA formulas?
A: Different studies produced slightly different formulas. Mosteller is most common, but Du Bois and Haycock are also used.

Q3: Is BMI accurate for athletes?
A: BMI may overestimate body fat in muscular individuals as it doesn't distinguish between muscle and fat mass.

Q4: When is BSA used in medicine?
A: BSA is used for chemotherapy dosing, cardiac index calculations, and glomerular filtration rate adjustments.

Q5: Should children use this calculator?
A: Children need BMI-for-age percentiles rather than standard BMI categories. BSA calculations are similar for all ages.