An adult of average build: 170 cm, 70 kg
Mosteller gives about 1.81 m², DuBois gives a very close 1.81 m² — the two formulas agree closely at typical adult proportions.
Body surface area calculator (Mosteller, DuBois)
For healthcare professional reference only. This is a formula-based estimate, not a substitute for a dosing protocol, a pharmacist’s verification or a treating clinician’s judgement. Never calculate or adjust a medication dose based solely on this page.
Result
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How it works
BSA approximates the total outer area of the body from just two measurements. It correlates better than body weight alone with metabolic rate and drug clearance for many medications, which is why chemotherapy and some other drug doses are conventionally expressed per square metre of BSA rather than per kilogram.
Mosteller’s formula (1987) is a simpler square-root relationship designed to be easy to compute by hand and is now the most widely used in practice. DuBois & DuBois (1916) was derived from a small number of direct surface measurements using coating and paper-pattern methods, and remains a historically important reference despite its narrow original sample.
Formulas used
Mosteller
BSA (m²) = √(height(cm) × weight(kg) / 3600)
DuBois & DuBois
BSA (m²) = 0.007184 × height(cm)^0.725 × weight(kg)^0.425
Worked examples
A child: 110 cm, 20 kg
At smaller body sizes the two formulas can diverge slightly more, which is one reason paediatric dosing protocols specify exactly which formula to use.
Assumptions and limits
- Both formulas are population-average approximations, not a direct physical measurement of an individual’s surface area.
- Neither formula accounts for body composition (muscle vs. fat) beyond what height and weight already capture.
Frequently asked questions
Which formula should I use?
Whichever your institution’s dosing protocol specifies — the two rarely differ enough to change a clinical decision for an average adult, but a specific chemotherapy regimen or paediatric protocol may name one explicitly, and that reference should be followed rather than a personal preference.
Why use BSA instead of weight alone for drug dosing?
BSA correlates more closely than weight with blood volume, cardiac output and metabolic rate across a wide range of body sizes, which historically made it a better predictor of appropriate dosing for drugs with a narrow therapeutic window, such as many chemotherapy agents.
Updated