Quick answer: At 170 cm and 70 kg the Mosteller formula gives √(170 × 70 ÷ 3600) = 1.82 m²; DuBois gives 1.81 m².
How it's calculated
Mosteller: BSA = √(height in cm × weight in kg ÷ 3600). It is a simplified form of earlier formulas and is widely used for drug dosing.
DuBois & DuBois (1916): BSA = 0.007184 × weight^0.425 × height^0.725. Haycock (1978): BSA = 0.024265 × weight^0.5378 × height^0.3964, derived from measurements that included infants and children.
BSA is used to scale doses of chemotherapy and some other drugs, and to index measures such as cardiac output and kidney function (eGFR is reported per 1.73 m²; see the eGFR calculator).
The formulas give similar results for typical adults but can differ by several percent at extremes of size, and none of them measures skin area directly. Dosing decisions follow the protocol and formula your care team uses.
Worked examples
- 170 cm, 70 kg: Mosteller √(170 × 70 ÷ 3600) = 1.82 m²
- 180 cm, 90 kg: Mosteller √(180 × 90 ÷ 3600) = 2.12 m²
- 160 cm, 55 kg: DuBois 0.007184 × 55^0.425 × 160^0.725 = 1.56 m²
Frequently asked questions
What is a normal body surface area?
For adults, about 1.6 to 2.0 m²; an average adult man is about 1.9 m² and woman about 1.6 m².
Which BSA formula should I use?
Mosteller is the simplest and the most widely used. DuBois is the historical standard. Haycock is often used for children.
Why is kidney function given per 1.73 m²?
1.73 m² was the average adult BSA when the convention was set, so eGFR is scaled to that size to compare people of different builds.
Why is body surface area used in medicine?
Metabolism and blood flow track body size better through surface area than through weight alone, so doses of some medicines, such as chemotherapy, are set per square metre.
How much does weight change the result?
Less than you might expect, because of the square root in the formula. With Mosteller, 10% more weight gives about 5% more surface area.
Does it work for children?
The Mosteller formula is also used for children, but a child's medicine dose should always be set by their doctor or pharmacist.