Body Surface Area Calculator
Estimate body surface area from height and weight using the Mosteller formula.
Try an example
1.82 m²
About this calculator
What Is Body Surface Area?
Body surface area (BSA) is the total area of the outside of the human body, measured in square meters. Doctors prefer it to body weight for many purposes because metabolic rate, blood volume and organ size relate more closely to surface area than to weight alone. The average adult has a BSA of roughly 1.7 m² (about 1.6 m² for women and 1.9 m² for men). Enter height and weight in this BSA calculator and it applies a standard formula to estimate your value.
BSA Formulas
Several equations are in common use. All take height and weight and give nearly the same answer for typical adults:
- Mosteller: BSA = √[ height (cm) × weight (kg) ÷ 3600 ] — the simplest and the most widely used.
- Du Bois: BSA = 0.007184 × weight0.425 × height0.725 — the original, from 1916.
- Haycock: BSA = 0.024265 × weight0.5378 × height0.3964 — often used for children.
- Gehan and George: BSA = 0.0235 × weight0.51456 × height0.42246 — developed from data that included infants and children.
A person who is 170 cm tall and weighs 70 kg has a Mosteller BSA of √(170 × 70 ÷ 3600) ≈ 1.82 m².
Worked Example
A person 170 cm tall weighing 70 kg has a body surface area of about 1.82 m² — close to the commonly cited "average adult" figure of roughly 1.7-1.9 m².
Why BSA Is Used in Medicine
- Chemotherapy dosing: many cancer drugs are dosed per square meter of BSA to match dose to body size.
- Cardiac index: cardiac output divided by BSA lets doctors compare heart function between patients of different sizes.
- Burn assessment: the share of body surface burned guides fluid replacement and treatment.
- Kidney function: glomerular filtration rate is often normalized to 1.73 m² of BSA.
- Metabolic research: comparing energy use across people of different sizes.
Limits to Keep in Mind
BSA formulas are estimates built from population averages, and they can be less accurate for very small or very large bodies, children, and people with unusual proportions. For medical decisions the figure is always interpreted by a clinician. If you are interested in other body measurements, see the BMI Calculator, the Body Fat Calculator and the Ideal Weight Calculator.
Worked example
At 170 cm and 70 kg, BSA = √(170 × 70 ÷ 3600) ≈ 1.82 m², using the Mosteller formula.
Frequently asked questions
What is body surface area used for?
It's most commonly used in medicine to calculate drug dosages (especially chemotherapy) and to assess metabolic and cardiac measurements, since these often scale more closely with BSA than with weight alone.
Why the Mosteller formula specifically?
Mosteller is simple and widely used in clinical practice; other formulas (DuBois, Haycock, Gehan-George) exist and can give slightly different results, but generally agree within a few percent.
Is this something I should use to dose medication myself?
No — dosing decisions should always be made by a healthcare provider using validated clinical tools, not a general calculator.
