Mosteller: BSA = √(height × weight / 3600)Body surface area is the calculated surface of the human body. Four formulas in clinical use give slightly different values. Mosteller is the simplest and most common; Du Bois is the oldest; Haycock is calibrated for children; Boyd accounts for variation across age groups. Results in m².
Enter height and weight. Get body surface area from four medical formulas.
Enter your height in centimeters and weight in kilograms to get your body surface area in square meters. The calculator uses four standard formulas (Mosteller, Du Bois, Haycock, Boyd) so you can see how each method compares. BSA is used for chemotherapy dosing, burn assessment, and pediatric medicine.
Body surface area is the calculated total area of your skin in square meters. Doctors use BSA to set chemotherapy doses, calculate cardiac output, and assess burn coverage. Several formulas exist because none perfectly fits every body type. This calculator runs the four most common in parallel.
Definition
The computation, step by step
- 1Enter your height in centimeters.
- 2Enter your weight in kilograms.
- 3The calculator applies four standard formulas.
- 4Mosteller is the simplest and most commonly used today.
- 5Du Bois, Haycock, and Boyd are shown for comparison.
- 6The average across all four is also given.
Solved example
A worked solution
Example: 170 cm, 70 kg adult, Mosteller formula
- 1Height × Weight = 170 × 70 = 11,900
- 211,900 / 3,600 = 3.306
- 3√3.306 = 1.818 m²
Validity
Edge cases and pitfalls
- Using imperial units in the formula: All four formulas expect height in cm and weight in kg. Mixing in pounds and inches gives results off by a factor of two or three.
- Picking the wrong formula for the patient: Mosteller is fine for adults. For children under 13, Haycock or Boyd are more accurate. For obesity, none of the formulas is perfect.
- Treating BSA as exact: Real BSA varies by body shape. The formulas are estimates; the four can disagree by 5-10% at extreme heights or weights.
- Confusing BSA with BMI: BMI measures relative weight (kg/m²). BSA measures skin area (m²). They are completely different quantities.
Adjacent topics
Related concepts
| Term | Definition |
|---|---|
| Mosteller formula | Simplest BSA formula, published in 1987. BSA = √(height in cm × weight in kg / 3600). Widely used in oncology. |
| Du Bois formula | The original 1916 BSA formula, derived from measurements of 9 subjects. Still common in cardiac and metabolic medicine. |
| Haycock formula | Developed for infants and children. Calibrated against a large pediatric sample. |
| Boyd formula | 1935 formula valid for the widest weight and age range. More complex; less commonly used clinically. |
Applications
Where this calculation appears
- Chemotherapy dosing: Most chemo doses are calculated per square meter of BSA, not per kilogram of body weight.
- Burn assessment: The Rule of Nines uses BSA estimates to quantify the area of a burn for treatment.
- Cardiac index: Cardiac output divided by BSA gives the cardiac index, a body-size-normalized measure of heart function.
- Pediatric medication: Drugs that need precise dosing in children often use BSA, especially with Haycock or Boyd formulas.
Implementation notes
Pro tips
- Use Mosteller for adult dosing: It is the standard in adult oncology and gives results within 1-2% of more complex formulas for normal-range body types.
- Use Haycock for pediatric patients: Haycock was calibrated against children. For patients under about 30 kg, it is the most accurate.
- Compare formulas at extremes: At very high or very low BMI, the four formulas disagree. Run all four and see the spread before committing to one value.
- Convert to ft² for intuition: 1 m² is about 10.76 square feet. A typical adult BSA of 1.8 m² is roughly 19.4 ft², about the area of a small bathroom mirror.
Common questions
Frequently asked questions
Quick reference
BSA Values by Height and Weight (Mosteller)
For typical adult ranges
| Height | Weight | BSA (m²) |
|---|---|---|
| 150 cm | 50 kg | 1.44 |
| 160 cm | 60 kg | 1.63 |
| 170 cmtypical | 70 kg | 1.82 |
| 180 cm | 80 kg | 2.00 |
| 190 cm | 90 kg | 2.18 |
For related calculations, try the BMI Calculator, BMR Calculator, or Ideal Weight Calculator. Browse all Calculator Online calculators for the full catalog.
Methodology
This calculator uses the standard body surface area calculator formula. Results match those from established financial, scientific, and health references.
Reviewed by
Calculator Online Editorial Team. All formulas verified against authoritative sources before publication.
Last updated
2026-05-24