BSA Calculator (Body Surface Area)
Calculate body surface area using the DuBois formula. BSA is used in medicine for drug dosing, burn assessment, cardiac index calculation, and renal function estimation.
This free online bsa calculator (body surface area) provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
How to Use This Calculator
Enter your input values
Fill in all required input fields for the BSA Calculator (Body Surface Area). Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The BSA Calculator (Body Surface Area) instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
Formula Reference
BSA Calculator (Body Surface Area) Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above. Input fields accept values in multiple unit systems — select your preferred unit from the dropdown next to each field.
When to Use This Calculator
- •Use the BSA Calculator (Body Surface Area) for personal health tracking and wellness monitoring, establishing a baseline and tracking changes over time.
- •Use it when recording fitness metrics to track progress toward health or athletic goals.
- •Use it to compare measurements before and after a lifestyle, diet, or training change to quantify the impact.
- •Use it as a conversation starter before a doctor's appointment, bringing objective data to discuss with a healthcare professional.
About This Calculator
The BSA Calculator (Body Surface Area) is a free health and wellness calculation tool designed for personal use and general informational purposes. Calculate body surface area using the DuBois formula. BSA is used in medicine for drug dosing, burn assessment, cardiac index calculation, and renal function estimation. This calculator provides reference values based on established health screening formulas and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Results may vary based on individual factors not captured by the calculation. Consult a qualified healthcare provider for personalized health guidance. All calculations are performed locally in your browser — no personal health data is transmitted or stored.
About BSA Calculator (Body Surface Area)
The BSA Calculator computes body surface area using the DuBois & DuBois formula, the most widely used method in clinical medicine. Body surface area is a better predictor of metabolic rate than body weight alone, making it essential for accurate drug dosing in chemotherapy, fluid resuscitation, cardiac output indexing, and burn injury assessment. The average adult BSA is approximately 1.7 m² for women and 1.9 m² for men. BSA-based dosing is particularly important in oncology where chemotherapy doses are calculated per m² of BSA.
The Math Behind It
Formula Reference
DuBois Formula
BSA = 0.007184 × height^0.725 × weight^0.425
Variables: height in cm, weight in kg
Worked Examples
Example 1: Average Adult Male
175 cm tall, 70 kg
BSA is approximately 1.85 m² — close to the average adult male BSA.
Example 2: Pediatric Patient
120 cm tall, 25 kg
BSA is approximately 0.93 m² — about half an adult.
Common Mistakes & Tips
- !Confusing height units — the DuBois formula requires centimeters, not meters or inches.
- !Using BSA interchangeably with BMI. BSA measures total skin area; BMI is a weight-to-height ratio.
- !Not accounting for amputations or extreme body habitus when BSA is used for drug dosing.
Related Concepts
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Frequently Asked Questions
Why is BSA used for chemotherapy dosing instead of weight?
BSA correlates better with metabolic rate, organ size, and drug clearance than weight alone. BSA-based dosing reduces the risk of toxicity in larger patients and underdosing in smaller patients.
What is a normal BSA?
Average adult BSA is approximately 1.7 m² for women and 1.9 m² for men. The range for adults is roughly 1.5 to 2.2 m². Newborns have a BSA of about 0.25 m².