BSA Calculator

Q: What is a normal BSA value?

Average adult BSA ranges between 1.6 m² and 2.1 m², depending on body size, gender, and weight.

Body Surface Area BSA Calculator

Body Surface Area (BSA) is a key measurement used in medical, health, and fitness contexts to assess an individual’s body size based on height and weight. Expressed in square meters (m²), BSA provides a standardized way to calculate dosages for medications, assess metabolic rates, or adjust clinical parameters like glomerular filtration rate (GFR) for more accurate health evaluations. Our free BSA Calculator offers a quick and precise way to determine your body surface area, making it an essential tool for healthcare professionals, patients, and fitness enthusiasts alike.

Curious about your body surface area (BSA) in square meters (m²)? Our intuitive BSA calculator makes it effortless to determine this key metric using just your height and weight. While the Du Bois formula serves as the default — widely trusted in medical settings — you can explore alternative methods for precision tailored to different populations.

What Is Body Surface Area (BSA)?

Body Surface Area (BSA) represents the total external surface area of the human body, expressed in square meters (m²).
It’s a more precise measurement than body weight alone because it accounts for both height and weight, offering a better reflection of metabolic mass.

Doctors, pharmacists, and researchers use BSA values to:

Calculate medication dosages (especially chemotherapy or pediatric drugs)
Estimate cardiac output and renal function
Assess fluid replacement needs
Evaluate metabolic rate and caloric needs

For example, drug doses for children and adults often differ, not only by weight but by body surface area, ensuring safety and accuracy.

Top BSA Formulas: From Du Bois to Fujimoto

No complex math required! Input your weight in kg and height in cm (our calculator handles conversions automatically). Here are the most reliable formulas:

1. Du Bois Formula (Default & Gold Standard)

$(m²)=0.007184×weight0.425×height0.725\text{BSA (m²)} = 0.007184 \times \text{weight}^{0.425} \times \text{height}^{0.725}$

Proven accurate across obese and non-obese adults.
Original source: Du Bois & Du Bois, 1916.

2. Mosteller Formula (Simplest for Quick Estimates)

$(kg)3600\text{BSA (m²)} = \sqrt{\frac{\text{height (cm)} \times \text{weight (kg)}}{3600}}$

Or: $BSA=0.016667×weight×height\text{BSA} = 0.016667 \times \sqrt{\text{weight} \times \text{height}}$
Ideal for bedside calculations.

3. Haycock Formula (Best for Infants & Children)

$(m²)=0.024265×weight0.5378×height0.3964\text{BSA (m²)} = 0.024265 \times \text{weight}^{0.5378} \times \text{height}^{0.3964}$

Validated across all ages.

4. Gehan & George Formula

$(m²)=0.0235×weight0.51456×height0.42246\text{BSA (m²)} = 0.0235 \times \text{weight}^{0.51456} \times \text{height}^{0.42246}$

Strong for pediatric and adult oncology.

5. Fujimoto Formula (Optimized for Japanese Populations)

$(m²)=0.008883×weight0.444×height0.663\text{BSA (m²)} = 0.008883 \times \text{weight}^{0.444} \times \text{height}^{0.663}$

Developed from extensive anthropometric studies.

How to Calculate BSA: Step-by-Step Example (Mosteller Method)

Let’s say you’re 170 cm tall and weigh 60 kg.

Manual Calculation:

Multiply height × weight: $170 \times 60 = 10,200$
Divide by 3,600: $\div 3,600 = 2.833$
Take the square root: $2.833≈1.68\sqrt{2.833} \approx 1.68$

Your BSA ≈ 1.68 m²

Using the Calculator:

Enter Weight: 60 kg
Enter Height: 170 cm
Result: ~1.68 m² (instant!)

Pro tip: The Du Bois method may yield ~1.69 m² — slight variations are normal.

Average BSA Values by Age and Gender

Wondering how you compare? Here are typical ranges:

Group	Average BSA (m²)
Newborn Infants	0.25
2-Year-Old Children	0.50
10-Year-Old Children	1.14
Adult Women	1.60
Adult Men	1.90

Values vary by ethnicity, build, and formula used.

When to Choose Different BSA Formulas

Use Case	Recommended Formula
General adult dosing	Du Bois or Mosteller
Pediatric patients	Haycock
Chemotherapy precision	Gehan & George
Asian populations	Fujimoto
Research or obesity studies	Du Bois (validated)

Use our free online BSA calculator now — no signup needed! Simply input:

Weight (kg, lbs, or st)
Height (cm, ft/in, or m)

Get instant results with formula comparisons.

Try it today and unlock a smarter way to understand your body’s true scale!

Disclaimer: This tool supports education and estimation. For medical decisions, always rely on professional healthcare advice.

Using our BSA Calculator empowers you to take control of your health and fitness journey. Whether you’re a healthcare provider needing precise measurements for patient care or an individual tracking wellness goals, this tool eliminates guesswork and enhances decision-making. Accessible and efficient, it supports a wide range of applications, from clinical diagnostics to personalized fitness plans, ensuring your calculations are both accurate and relevant.

FAQ

What is a BSA Calculator?

A BSA Calculator estimates the total surface area of your body using your height and weight — important for drug dosing and medical calculations.

How is BSA calculated?

BSA is calculated using formulas like Mosteller:

$\sqrt{\frac{Height (cm) × Weight (kg)}{3600}}$

What is a normal BSA value?

Average adult BSA ranges between 1.6 m² and 2.1 m², depending on body size, gender, and weight.

Why is BSA used in medicine?

BSA is used to calculate medication doses, IV fluids, kidney function, and cardiac index, providing a more accurate measure than weight alone.

Which BSA formula is most accurate?

The Mosteller formula is the simplest and most widely used in hospitals because it offers excellent accuracy with minimal complexity.

BSA Calculator – Body Surface Area