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BSA/BMI Calculator

BSA/BMI Calculator

Calculate Body Mass Index (BMI) and Body Surface Area (BSA) with multiple formulas and unit conversions. Essential for health assessment, medical dosing, and fitness monitoring.

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Body Mass Index & Body Surface Area Calculator
Enter your measurements to calculate BMI and BSA with health interpretations

Normal range: 4-660 lbs

Normal range: 20-98 in

Different formulas may give slightly different BSA values

Healthy range: 18.5 - 24.9 kg/m²

Example Calculations
Sample BMI and BSA values for different body measurements
70 kg, 175 cm
BMI: 22.9 kg/m²
BSA: 1.85 m² (Mosteller)
150 lbs, 68 in
BMI: 22.8 kg/m²
BSA: 1.74 m² (Mosteller)
80 kg, 180 cm
BMI: 24.7 kg/m²
BSA: 2.00 m² (Mosteller)
130 lbs, 64 in
BMI: 22.3 kg/m²
BSA: 1.56 m² (Mosteller)
BMI Calculation Formula
Body Mass Index is calculated using your weight and height

Standard BMI Formula (Metric)

BMI=Weight (kg)Height (m)2\text{BMI} = \frac{\text{Weight (kg)}}{\text{Height (m)}^2}

The most common formula used worldwide

Imperial Units Formula

BMI=Weight (lbs)×703Height (in)2\text{BMI} = \frac{\text{Weight (lbs)} \times 703}{\text{Height (in)}^2}

Multiply by 703 to convert from imperial to metric units

📊 Example Calculation:

Person: 70 kg weight, 1.75 m tall

BMI=701.752=703.0625=22.9 kg/m2\text{BMI} = \frac{70}{1.75^2} = \frac{70}{3.0625} = 22.9 \text{ kg/m}^2

Result: Normal Weight\text{Normal Weight} (18.5-24.9 range)

BSA Calculation Formulas
Three commonly used formulas for Body Surface Area calculation
Mosteller Formula\text{Mosteller Formula}
Most Common
BSA (m2)=Height (cm)×Weight (kg)3600\text{BSA (m}^2\text{)} = \sqrt{\frac{\text{Height (cm)} \times \text{Weight (kg)}}{3600}}

Recommended for general use, simple and accurate

Du Bois Formula\text{Du Bois Formula}
Most Accurate
BSA (m2)=0.007184×Weight (kg)0.425×Height (cm)0.725\text{BSA (m}^2\text{)} = 0.007184 \times \text{Weight (kg)}^{0.425} \times \text{Height (cm)}^{0.725}

Gold standard, widely used in clinical practice

Haycock Formula\text{Haycock Formula}
Pediatric Use
BSA (m2)=0.024265×Weight (kg)0.5378×Height (cm)0.3964\text{BSA (m}^2\text{)} = 0.024265 \times \text{Weight (kg)}^{0.5378} \times \text{Height (cm)}^{0.3964}

Better accuracy for children and adolescents

🧮 Example (Mosteller):

Person: 175 cm tall, 70 kg weight

BSA=175×703600=122503600=3.403=1.845 m2\text{BSA} = \sqrt{\frac{175 \times 70}{3600}} = \sqrt{\frac{12250}{3600}} = \sqrt{3.403} = 1.845 \text{ m}^2
What is BMI and Why It Matters?

Body Mass Index (BMI) is a measure of body fat based on height and weight. It's a screening tool used to categorize weight status and assess health risks.

BMI Categories:

  • Underweight: BMI < 18.5
  • Normal weight: BMI 18.5-24.9
  • Overweight: BMI 25-29.9
  • Obesity: BMI ≥ 30

Limitations:

  • Doesn't distinguish between muscle and fat
  • May not be accurate for athletes or elderly
  • Should be combined with other health metrics
Understanding BSA (Body Surface Area)

Body Surface Area is the total surface area of the human body. It's crucial for medical calculations, especially drug dosing and metabolic assessments.

BSA Formulas:

  • Mosteller: Most commonly used, simple calculation
  • Du Bois: Most accurate, gold standard
  • Haycock: Better for pediatric patients

Clinical Applications:

  • Chemotherapy drug dosing
  • Burn treatment calculations
  • Cardiac output assessment
  • Renal function evaluation
How to Use BMI/BSA for Health Management

Medical Applications

  • • BMI for health risk assessment
  • • BSA for precise drug dosing
  • • Combined metrics for comprehensive evaluation
  • • Regular monitoring for health tracking

Fitness Goals

  • • BMI trends for weight management
  • • BSA affects metabolic rate calculations
  • • Combine with body composition analysis
  • • Set realistic target ranges

Combined Metrics

  • • Use with waist-hip ratio (WHR)
  • • Include body fat percentage
  • • Consider muscle mass distribution
  • • Regular health check-ups

Frequently Asked Questions

BMI (Body Mass Index) measures body fat based on height and weight. Formula: BMI = weight(kg) / height(m)². For US units: BMI = weight(lb) × 703 / height(in)². A BMI of 18.5-24.9 is considered healthy for most adults.
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BMI & BSA Calculator - Body Mass Index & Surface Area | MathIsimple