Body surface area calculator.

Worked example

Height 170 cm, weight 70 kg. Mosteller: the square root of (170 × 70 ÷ 3600) = the square root of 3.3056 = 1.82 m² (18,181 cm²). Du Bois: 0.007184 × 70^0.425 × 170^0.725 = 1.81 m². The two agree to about 0.01 m² here. In US units, 67 in and 154 lb convert to 170.2 cm and 69.9 kg and give 1.82 m² (Mosteller).

How it works

Mosteller: BSA (m²) = √(height in cm × weight in kg ÷ 3600). Du Bois and Du Bois: BSA (cm²) = 71.84 × weight^0.425 (kg) × height^0.725 (cm), divided by 10,000 for m². Both are estimates fitted to groups of people, not measurements of your skin.

For scale, RxList gives about 1.7 m² as a commonly used “normal” value and notes that body surface area also depends on age and gender, with averages of 1.9 m² for adult men and 1.6 m² for adult women.

What this is not. It is not a dosing tool. Medicines and prescription creams are dosed by the label or the prescriber. For how much cream covers an area, see the fingertip unit calculator.

Sources and basis (opened 2026-10-08): Wikipedia, Body surface area (Mosteller and Du Bois formulas and constants); RxList, Medical Definition of Body surface area (Mosteller 1987 formula, 1.7 m2 and group averages).

FAQ

What is the Mosteller formula for body surface area?

BSA in square metres is the square root of height in centimetres times weight in kilograms, divided by 3600. It was published by Mosteller in 1987 as a simplified version of older formulas.

Mosteller or Du Bois: which should I use?

They usually land within a few hundredths of a square metre of each other. For 170 cm and 70 kg the tool gives 1.82 m2 (Mosteller) and 1.81 m2 (Du Bois). Use the one your source or clinic names; Mosteller is the easier to do by hand.

What is a normal body surface area?

RxList gives about 1.7 m2 as a commonly used normal value, with averages of 1.9 m2 for adult men and 1.6 m2 for adult women. It depends on height, weight, age and gender, so there is no single right number.

Can I use body surface area to work out how much cream or medicine to use?

No. Follow the product label or your prescriber. This tool only estimates surface area from height and weight and does not give a dose.

Is body surface area the same as the area covered by a cream or sunscreen?

No. It is a whole-body estimate. How much product covers a given area is a separate question; see the fingertip unit and sunscreen amount calculators.