Calculate your Body Surface Area (BSA) in m² using five established medical formulas. BSA is used in clinical dosing, burn treatment, and cardiac output calculations.
The average adult BSA is approximately 1.7 m² (range: 1.5–2.1 m²).
| Formula | Common Use |
|---|---|
| Mosteller | Simplest; widely used in oncology |
| DuBois & DuBois | Most historically referenced |
| Haycock | Preferred for pediatric patients |
| Gehan & George | Large-population derived |
| Boyd | Accurate across wide weight range |
| Formula | BSA (m²) |
|---|---|
| Mosteller | 1.845 |
| DuBois & DuBois | 1.848 |
| Haycock | 1.847 |
| Gehan & George | 1.854 |
| Boyd | 1.851 |
| Average | 1.849 |
| Group | Average BSA |
|---|---|
| Neonate | 0.25 m² |
| Child (2 years) | 0.5 m² |
| Child (10 years) | 1.14 m² |
| Adult female | 1.6 m² |
| Adult male | 1.9 m² |
BSA is commonly used for drug dosing, especially chemotherapy, where doses are expressed per m² of body surface area.
Double your weight and your body surface area does not double. At 175 cm, going from 70 kg to 140 kg lifts BSA from 1.849 m² to 2.622 m², an increase of about 42 percent. At 70 kg the five formulas on this page agree to within 0.009 m², but at 140 kg they spread across 0.211 m², roughly 8 percent. This calculator shows all five side by side, with their average, so you can see when the choice of formula starts to matter.
Typical case: 175 cm and 70 kg. Mosteller (1987): BSA = √(height in cm × weight in kg ÷ 3600) = √(12,250 ÷ 3600) = √3.4028 = 1.845 m². Du Bois and Du Bois (1916): 0.007184 × H^0.725 × W^0.425 = 1.848. Haycock (1978): 0.024265 × H^0.3964 × W^0.5378 = 1.847. Gehan and George (1970): 0.0235 × H^0.42246 × W^0.51456 = 1.854. Boyd: 0.0003207 × H^0.3 × (W in grams)^(0.7285 − 0.0188 × log10(grams)) = 1.851. The page rounds each result to three decimals and then averages those five, giving 1.849 m².
Edge case, pounds typed into the kilogram field. Entering 154 as kg at 175 cm returns an average of 2.751 m² (Mosteller 2.736) instead of 1.849 m², about 49 percent too high. The field's 10 to 300 kg limits are only hints, and 154 sits inside them, so nothing flags the mistake. Check the units selector before trusting the result. If height or weight is blank or zero, the page shows no result at all.
A note on use. BSA is the denominator behind lab eGFR, which KDIGO guidance reports per 1.73 m², and it is also used in drug dosing. The five-formula average here is a general-education figure. Clinicians and pharmacists work from the single formula their institution specifies, and the 2012 ASCO guideline on chemotherapy dosing in obesity advises using actual body weight. This page is not medical advice and should not be used to calculate a dose.
Mosteller is the simplest and widely used for adults, Du Bois is the historical reference, and Haycock is often cited for children. If a hospital or protocol names one formula, that is the one to use, not the page average.
No. Doses are set by the treating team and pharmacist under their own protocols and rounding rules. This page is for education only and is not medical advice.
It runs the same formulas, but the weight field is meant for 10 kg and up and the height field for 100 cm and up. Children's measurements and any dosing belong with a pediatric clinician, who will use their own protocol.
Lab eGFR is reported in mL/min per 1.73 m², a conventional average adult BSA. A measured clearance of 90 mL/min in someone with a BSA of 2.0 m² corresponds to about 78 mL/min/1.73 m², since 90 × 1.73 ÷ 2.0 is about 77.9.
No. The reference values are rough group averages, not targets or limits. Individual BSA varies with height and weight, and anything from about 1.5 to 2.1 m² is ordinary for adults.