How to use it
- Choose metric or imperial units and enter height and weight.
- All five formulas are calculated at once; pick the one your protocol uses as the headline with the formula switch.
- Read the spread between formulas to see how much the choice of equation matters for your values.
- Copy the summary (all five values) or the link for your records.
Example
Height 170 cm, weight 70 kg. Mosteller: √(170 × 70 ÷ 3600) = √3.306 = 1.818 m². Du Bois: 0.007184 × 1700.725 × 700.425 = 1.810 m². A chemotherapy dose of 100 mg/m² would therefore be 182 mg with Mosteller and 181 mg with Du Bois – the difference between formulas is usually smaller than the rounding applied in practice. A 3.5 kg, 50 cm newborn has a Haycock BSA of 0.22 m².
Formulas and when each is used
Mosteller 1987: BSA = √(height × weight ÷ 3600)
Du Bois 1916: BSA = 0.007184 × height^0.725 × weight^0.425
Haycock 1978: BSA = 0.024265 × height^0.3964 × weight^0.5378
Gehan & George 1970: BSA = 0.0235 × height^0.42246 × weight^0.51456
Boyd 1935: BSA = 0.0003207 × height^0.3 × grams^(0.7285 − 0.0188 × log10 grams)
height in cm, weight in kg (Boyd: grams), result in m²; 1 m² = 10.764 ft²Du Bois and Du Bois fitted their formula on only nine subjects, yet it remained the standard for most of the 20th century. Gehan and George used 401 direct measurements; Haycock’s equation was validated from infants to adults; Boyd allowed the weight exponent to shrink with weight. Mosteller simplified the geometric mean of height and weight into a formula that can be done on a pocket calculator and it is now the default in most oncology dosing software. All formulas describe lean, healthy bodies of their era; in severe obesity they may overestimate the dosing-relevant area, which is why some protocols cap BSA at 2.0–2.2 m². The previous version of this page displayed the Haycock value in the Gehan & George field by mistake; this one computes each formula separately and is covered by tests.
Sources: Mosteller 1987, N Engl J Med 317:1098, Du Bois & Du Bois 1916, Arch Intern Med 17:863, Haycock et al. 1978, J Pediatr 93:62, Gehan & George 1970, Cancer Chemother Rep 54:225, Boyd 1935, The Growth of the Surface Area of the Human Body.
This calculator is for information only. Drug doses based on BSA must be checked by a prescriber or pharmacist using the formula and rounding rules of the specific protocol.
Typical BSA values
| Person | Approximate BSA |
|---|---|
| Newborn (3.5 kg, 50 cm) | 0.21–0.22 m² |
| Child aged 10 (32 kg, 138 cm) | 1.1 m² |
| Adult woman (60 kg, 165 cm) | 1.66 m² |
| Adult man (75 kg, 178 cm) | 1.93 m² |
| eGFR reference body | 1.73 m² |
Questions
- Which BSA formula should I use?
- Use the one your clinical protocol names. Most chemotherapy regimens and dosing software use Mosteller; older references and many cardiac tables use Du Bois; paediatric guidelines often use Haycock.
- Why is kidney function reported per 1.73 m²?
- 1.73 m² was the average BSA of young American adults in the 1920s and became the reference body for normalising glomerular filtration rate so that results are comparable between people of different size.
- Does BSA work for very heavy people?
- The formulas keep rising with weight, but fat tissue contributes little to drug clearance, so many protocols cap the BSA used for dosing at about 2.0–2.2 m² or use an adjusted weight. Follow the protocol, not the raw number.