Health and fitness tools
Body Surface Area Calculator
Estimate body surface area from height and weight with the Mosteller, Du Bois, and Haycock formulas plus an average and per-kilogram ratio locally in your browser.
Enter your height and weight to compare three standard body surface area formulas (Mosteller, Du Bois, and Haycock) plus an average and the per-kilogram ratio. Calculations run locally in your browser; your values are not uploaded or stored.
Compare three standard body surface area formulas.
Enter your height and weight in centimetres and kilograms, or feet, inches, and pounds, and the calculator applies three classic body surface area equations. Mosteller is √(height × weight ÷ 3600), Du Bois is 0.007184 × height^0.725 × weight^0.425, and Haycock is 0.024265 × height^0.3964 × weight^0.5378, with height in centimetres and weight in kilograms. For example, 175 cm and 70 kg (5 ft 8.9 in and 154 lb) give Mosteller 1.845 m², Du Bois 1.848 m², and Haycock 1.847 m². The result also shows the average of the three formulas, the area in square centimetres, and the Mosteller ratio in m²/kg, which some dosing references use as a sanity check. Body surface area equations were derived from small adult and paediatric samples and vary between individuals, so treat the spread as a range rather than an exact measurement. This is a general estimate, not medical advice; dosing decisions must be made by a clinician. Your values are not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How does the body surface area calculator work?
Enter your height and weight, and the calculator applies three published equations. Mosteller: BSA = sqrt(height cm x weight kg / 3600). Du Bois: BSA = 0.007184 x height cm^0.725 x weight kg^0.425. Haycock: BSA = 0.024265 x height cm^0.3964 x weight kg^0.5378. For 175 cm and 70 kg the three give about 1.845, 1.848, and 1.847 square metres, and the calculator also shows the average of the three.
What is body surface area used for?
BSA estimates the outer surface of the body in square metres. Clinicians have used it to scale some drug doses and fluid volumes, and it also appears in burn-area estimates (the Rule of Nines and Lund-Browder charts) and kidney-function formulas such as GFR indexed to 1.73 m². It is a population-based estimate, not a direct measurement.
Why do the formulas give different numbers?
Mosteller (1987), Du Bois and Du Bois (1916), and Haycock (1978) were each fitted to different, small sets of measured subjects, mostly European and American adults and children, using different measurement techniques such as body prints and linear models. They usually agree within a fraction of a percent for typical adult sizes, so treat the spread as a small uncertainty band rather than picking one formula as exact.
Which inputs are accepted?
Enter a height from 40 cm to 230 cm (about 1 ft 4 in to 7 ft 6 in) and a weight from 2 kg to 300 kg (about 4 lb to 661 lb). These wide bounds include infants and large adults because the Haycock formula in particular is often used for children. Missing, non-numeric, or out-of-range entries show a clear error instead of a result.
Is this a medical measurement or advice?
No. BSA equations are population averages and do not account for body composition, pregnancy, oedema, amputation, or measurement technique, so individual values can differ by several percent. Any dosing or clinical decision must be made by a qualified healthcare professional using an approved method. This calculator is an educational estimate, and your values are calculated and copied locally in your browser, not uploaded or stored.