Body Surface Area Calculator
Calculate your BSA result in seconds with the free Body Surface Area Calculator. No registration needed.
Measurements
BSA
What is a Body Surface Area Calculator?
A Body Surface Area (BSA) Calculator estimates the total surface area of your body in square metres (m²). BSA is a key metric used in medical fields such as oncology, anaesthesiology, and nephrology to determine appropriate drug dosages and assess metabolic function.
How to calculate BSA manually (the formula)
The Mosteller formula is the most common method:
BSA (m²) = √(height in cm × weight in kg / 3600)
Take your height in centimetres, multiply by your weight in kilograms, divide by 3600, then take the square root of the result. The answer is your estimated BSA in square metres.
Example calculation
A person who is 175 cm tall and weighs 72 kg: BSA = √(175 × 72 / 3600) = √(12,600 / 3600) = √3.5 ≈ 1.87 m². This falls within the typical adult range.
Common mistakes
- Using the wrong units — Height must be in centimetres and weight in kilograms. Using inches or pounds will give an incorrect result.
- Forgetting the square root — The formula requires a square root after the division. Skipping it overestimates BSA by a factor of roughly 60.
- Confusing BSA with BMI — BSA measures surface area, not body fat. They are different metrics used for different clinical purposes.
Frequently asked questions
What is BSA used for?
BSA is used in medical dosing for chemotherapy, anesthesia, and renal function tests. It gives a more accurate measure of metabolic mass than body weight alone.
Which BSA formula does this calculator use?
This calculator uses the Mosteller formula: BSA (m²) = √(height in cm × weight in kg ÷ 3600). It is one of the most widely adopted clinical formulas.
What is a normal BSA?
The average adult BSA ranges from about 1.6 to 1.9 m². Normal values vary by age, sex, and body composition so there is no single “normal” for everyone.
Why is BSA important for medication dosing?
Many drugs, especially chemotherapy agents and anesthetics, are dosed per m² of BSA to better account for individual body size and reduce the risk of toxicity.
How accurate is BSA for medical decisions?
BSA is a useful clinical estimate but has limitations. Always follow your healthcare provider’s guidance for any medical decisions.
Does this calculator handle children?
Yes, the Mosteller formula works for children as well as adults. Enter the child’s height in cm and weight in kg for an estimate.