Body Surface Area Formula Calculator
Compare body surface area (BSA) estimates using five established height-and-weight formulas. Results are formula references for educational purposes and are not suitable for medication dosing, treatment decisions or clinical care.
BSA formula estimates
| Formula | Estimated BSA |
|---|---|
| Mosteller (1987) | 1.82 m² |
| Du Bois & Du Bois (1916) | 1.81 m² |
| Haycock (1978) | 1.83 m² |
| Gehan & George (1970) | 1.83 m² |
| Fujimoto (1968) | 1.76 m² |
For general information only. These formula estimates are not a medical assessment and do not replace advice from a qualified healthcare professional.
Do not use this calculator for medication dosing or treatment decisions.
How to use this body surface area calculator
- Enter a height, and pick its unit — centimetres, metres, feet, inches, or feet and inches.
- Enter a weight, and pick its unit — kilograms, pounds, or stones and pounds.
- Read the estimate from each of the five formulas in the comparison table.
Nothing is submitted anywhere. The calculation runs in the page as you type, and the link in your address bar carries the figures, so it can be shared or bookmarked.
How is body surface area calculated?
Each formula is calculated independently from height and weight. Every one takes height in centimetres and weight in kilograms, so any unit you enter is converted first. Because the equations use different coefficients and different height and weight exponents, their results may differ for the same measurements.
This page intentionally displays the individual formula estimates rather than one averaged or recommended body surface area. A clinical setting may require a particular validated formula and professional judgement, which is a decision for a prescriber or protocol, not for this calculator.
- Du Bois & Du Bois = 0.007184 × Height [cm]0.725 × Weight [kg]0.425
- Haycock = 0.024265 × Height [cm]0.3964 × Weight [kg]0.5378
- Gehan & George = 0.0235 × Height [cm]0.42246 × Weight [kg]0.51456
- Fujimoto = 0.008883 × Height [cm]0.663 × Weight [kg]0.444
Worked example. At 170 cm and 70 kg, the Mosteller formula gives √(170 × 70 ÷ 3600) = 1.82 m². For the same measurements Du Bois & Du Bois gives 1.81 m², Haycock 1.83 m², Gehan & George 1.83 m² and Fujimoto 1.76 m² — for an average adult build the five formulas typically sit within about a tenth of a square metre of one another.
Limitations of body surface area formulas
- Every formula is an estimate fitted to a limited historical sample, not a direct measurement of a person's body.
- Results can diverge more for people well outside an average adult height and weight range.
- This is a formula reference for general adult use, not a medical assessment. Do not use it for medication dosing, chemotherapy dosing, fluid or burn treatment, or other clinical decisions.
- It is not designed for paediatric or clinical use, and it does not replace advice from a qualified healthcare professional.