Estimate body surface area (BSA) from height and weight. See the Mosteller result alongside a Du Bois estimate, with cm/in and kg/lb unit choices.
Body Surface Area (BSA) Calculator
Mosteller body surface area
m²Mosteller: √[height (cm) × weight (kg) ÷ 3600]
Du Bois comparison estimate
m²Du Bois: 0.007184 × height (cm)^0.725 × weight (kg)^0.425
What the result means
BSA is an estimate of body surface area from height and weight. The two formulas can differ slightly; that difference is not a normal or abnormal health classification. Use the same formula for comparisons over time.
Limits
BSA is estimated by empirical equations, not measured directly. Unusual body habitus, edema or amputation may increase error. Do not use this page alone to set a medication dose or treatment; a clinician must account for weight, organ function and the treatment protocol.
What to check next
Check when height and weight were measured and which units were used. If comparing past results, check that the same equation was used. For a test or treatment that uses BSA, ask which equation and rounding rule the institution uses.
Questions for a visit
- Which BSA equation and rounding rule does this test or treatment use?
- Should BSA be recalculated after a weight change or edema?
- Are there cautions when interpreting another test indexed to BSA?
Inputs are calculated in this browser and are not automatically stored or sent to the site. Printing or saving a PDF includes the values.
How to use it and example
For a height of 170 cm and a weight of 70 kg, Mosteller BSA is √(170 × 70 ÷ 3600) ≈ 1.818 m². Du Bois gives about 1.810 m². No automatic normal interval is assigned.
What the result means
BSA is an estimate of body surface area from height and weight. The two formulas can differ slightly; that difference is not a normal or abnormal health classification. Use the same formula for comparisons over time.
Limits
BSA is estimated by empirical equations, not measured directly. Unusual body habitus, edema or amputation may increase error. Do not use this page alone to set a medication dose or treatment; a clinician must account for weight, organ function and the treatment protocol.
Frequently asked questions
Why do the formulas give different numbers?
The equations combine height and weight differently. They may give slightly different estimates for the same person. Confirm which formula is used for records or treatment.
Can I calculate a medicine dose from this number?
No. Prescribing also requires drug-specific instructions, dose caps, organ function, weight context and clinical judgment. This tool does not calculate doses.
Related calculators and records
BMI calculator · Weight and waist log · eGFR calculator · Health records and visit preparation
Sources
- Mosteller RD, Simplified Calculation of Body-Surface Area (1987)
- Du Bois D, Du Bois EF, surface area formula (1916)
- FDA prescribing information: Mosteller equation
General health information, not a substitute for medical care or prescribing. No independent clinician review is claimed. · Sources checked 2026-09-30