Body Surface Area Calculator
Calculate your body surface area from height and weight.
Your details
This tool is for general education only and is not medical advice. Talk to a healthcare professional about your results.
Body surface area (BSA) estimates the total external area of your body in square meters. It is mainly a clinical measurement, used in medicine for tasks such as calculating certain drug doses and, in kidney care, for standardizing filtration rates.
How BSA is calculated
Several validated formulas estimate BSA from just your height and weight. This tool shows three of the most common: Mosteller, which is the simplest and most widely used in practice, along with Du Bois and Haycock for comparison. The results are usually close to one another.
What the number means
The average adult body surface area is around 1.7 square meters, though it varies with height and weight. In clinical settings, BSA can give a more proportional basis for dosing than body weight alone, which is why it appears on many medical calculators.
BSA and fitness
For everyday fitness, body surface area is interesting to know but rarely relevant. The numbers that actually move your results are your calories, your macros, and your training. If those are your goals, SmaartCoach focuses on exactly that.
This tool is for general education only. Any medical use of body surface area, such as medication dosing, must be handled by a qualified healthcare professional.
Frequently asked questions
What is body surface area?
Body surface area (BSA) is the total surface area of the human body, expressed in square meters. It is used in medicine, for example to guide certain drug dosages.
Which BSA formula is best?
The Mosteller formula is the most widely used because it is simple and accurate. We also show Du Bois and Haycock for comparison.
What is an average BSA?
The average adult BSA is around 1.7 square meters, though it varies with height and weight.
Do I need BSA for fitness?
Not usually. BSA is mainly a clinical measure. For fitness, your calories, macros, and training matter far more.
Sources
Reviewed against these authoritative references. Last updated August 2026.
- National Kidney Foundation. Estimated Glomerular Filtration Rate (eGFR)
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). Chronic Kidney Disease Tests & Diagnosis
- MedlinePlus, U.S. National Library of Medicine. Metabolism
Turn these numbers into a real plan
Max builds your meals and workouts around your goal, then coaches you through it. Start free.
Get my plan with Max