Body Surface Area Calculator
Estimate body surface area in square meters from height and weight, by the Mosteller, Du Bois and Haycock formulas side by side.
Body surface area (BSA) is an estimate of the outer area of the body, in square meters, worked out from height and weight. The Mosteller formula takes the square root of height in cm times weight in kg, divided by 3600. For 170 cm and 70 kg that gives 1.82 m². The Du Bois formula gives 1.81 m² and the Haycock formula 1.83 m².
This calculator is for general education only. It is not medical advice and must not be used to calculate or check a medicine dose. Body surface area is an estimate from height and weight, and the three formulas credited below give slightly different results, more so for very small or very large bodies. Clinical uses follow the formula, rounding and limits set by the treating team's protocol. If you have a question about a treatment or dose, ask a doctor, pharmacist or another qualified health professional.
Body surface area (Mosteller)
1.82 m²
- Mosteller (1987)
- 1.82 m²
- Du Bois and Du Bois (1916)
- 1.81 m²
- Haycock (1978)
- 1.83 m²
Estimates from height and weight, rounded to two decimals. Not for working out a medicine dose.
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About the Body Surface Area Calculator
Body surface area cannot be measured with a tape, so it is estimated from height and weight with a formula fitted to people whose surface was measured directly. Mosteller (1987) is the square root of height in cm times weight in kg over 3600, offered by its author as a simpler form close to the older formulas. Du Bois and Du Bois (1916) is 0.007184 x weight^0.425 x height^0.725, where 0.007184 is their constant of 71.84 cm² divided by 10000, which turns the result into square meters. Haycock and colleagues (1978) is 0.024265 x weight^0.5378 x height^0.3964, checked in infants, children and adults. For 69 in and 180 lb, the calculator converts to 175.26 cm and 81.6 kg (2.54 cm to the inch, 0.45359237 kg to the pound), then gives 1.99 m² by Mosteller, 1.98 m² by Du Bois and 2.01 m² by Haycock. The formulas agree closely for most adults and drift apart for very small or very large bodies, so the page shows all three. Clinicians use body surface area to scale some medicine doses under their own protocols; this page explains how the number is worked out.
Frequently asked questions
How do I calculate body surface area?+
With the Mosteller formula, multiply height in cm by weight in kg, divide by 3600 and take the square root. For 170 cm and 70 kg: 170 x 70 = 11900; dividing that by 3600 and taking the square root gives 1.82 m². The calculator does this and shows two other formulas next to it.
Which body surface area formula is used most?+
This page does not rank the formulas by how often they are used. Mosteller is the easiest to work by hand. Each hospital or protocol names the formula it uses, so the right one for a given purpose is the one that protocol names.
Why do the formulas give different answers?+
Each was fitted to different people measured by different methods. Haycock and colleagues tested their formula in infants, children and adults, so it covers a wider range than Du Bois and Du Bois. For most adults the results differ by a few hundredths of a square meter.
Can I use this to work out a medicine dose?+
No. Doses based on body surface area are set by a prescriber or pharmacist under a protocol that names its formula, rounding and limits. Use this page to understand the number, and ask the person in charge of the treatment about any dose.
Formulas: Mosteller RD, Simplified calculation of body-surface area, N Engl J Med 1987;317:1098. Du Bois D, Du Bois EF, A formula to estimate the approximate surface area if height and weight be known, Arch Intern Med 1916;17:863-871. Haycock GB, Schwartz GJ, Wisotsky DH, Geometric method for measuring body surface area, J Pediatr 1978;93:62-66.
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