For healthcare professionals
Body Surface Area Calculator
Body surface area (BSA) is estimated from weight and height. It is used to scale measures such as kidney function and some drug doses to body size. This tool shows two widely used formulas, Du Bois and Mosteller, side by side. It is written for clinicians and is not a dosing tool or a diagnosis.
Weight and height
Use measured weight and height. Nothing you enter leaves this page.
What you will see
The body surface area by the Du Bois and the Mosteller formula, with the working.
Educational only, not medical advice. Not a diagnosis. Decisions belong to the treating team.
Source
The Du Bois and Mosteller formulas as printed in Table 1 of Mohamed AAA and colleagues, Nephrology Dialysis Transplantation 2026, an open-access (CC BY) review, with Du Bois also as printed by Redlarski G and colleagues, Scientific Reports 2016 (CC BY). The tests check Du Bois against the two worked examples in Mohamed 2026, Mosteller at exact values, and the input limits.
Validated in
Du Bois was derived in 1916 from nine people (six males and three females, including one child and one person with obesity). Mosteller was introduced in 1987 as a simplified form of the Gehan and George equation, which was based on 401 infants, children and adults (Mohamed 2026).
Limits
BSA formulas disagree. Across 25 formulas, results differed by up to 0.5 m² for a standard adult build, and Du Bois and Haycock differed by up to 0.82 m² at a high weight (Redlarski 2016). Du Bois has been reported to overestimate BSA in larger people and underestimate it in smaller ones (Mohamed 2026). This tool does not dose any drug.
The formulas
With weight in kilograms and height in centimetres (Mohamed 2026) (Redlarski 2016):
- Du Bois: BSA (m²) = 0.007184 x weight0.425 x height0.725.
- Mosteller: BSA (m²) = (weight0.5 x height0.5) / 60.
Worked examples from Mohamed 2026: a man 1.50 m tall weighing 50 kg has a BSA of 1.43 m², and a man 1.90 m tall weighing 80 kg has a BSA of 2.08 m². This tool gives the same values with Du Bois (Mohamed 2026). Pounds and inches are converted to kilograms and centimetres first.
Where BSA is used
Kidney function (GFR) is usually indexed to a standard BSA of 1.73 m², a reference value first proposed in 1928 and derived with the Du Bois equation. The review notes that average adult BSA has since risen, with US estimates for 2025 near 1.92 m² (2.03 m² for men and 1.81 m² for women). For drug dosing, the review favors non-indexed GFR, and notes that the American Society of Clinical Oncology recommends actual body weight when calculating BSA for chemotherapy dosing (Mohamed 2026).
How much the formulas differ
Redlarski and colleagues compared 25 BSA formulas and found that the choice of formula can change the result enough to matter, especially for people with an unusual build and for children. For an average 6-year-old boy (20.6 kg, 115.5 cm), the formulas ranged from 0.66 m² to 0.927 m² (Redlarski 2016).
Related tools
For kidney function, see the eGFR calculator (indexed to 1.73 m²) and the creatinine clearance calculator. Other bedside scores are listed under For healthcare professionals. For ideal and adjusted body weight, see the ideal body weight calculator.
Sources
- Mohamed AAA, van Londen M, Stevens J, Heerspink HJL, Gansevoort RT. Indexing for body surface area when assessing kidney function. Nephrol Dial Transplant. 2026;41(9):1595. doi:10.1093/ndt/gfag063. PMID 41860431. Open access (CC BY). Table 1 (Du Bois and Mosteller equations), worked examples (1.43 and 2.08 m2), the 1.73 m2 standard and drug dosing. pmc.ncbi.nlm.nih.gov/articles/PMC13518093/
- Redlarski G, Palkowski A, Krawczuk M. Body surface area formulae: an alarming ambiguity. Sci Rep. 2016;6:27966. doi:10.1038/srep27966. PMID 27323883. Open access (CC BY). Table 1 (25 BSA formulas, weight in kg and height in cm), Abstract and Results (differences between formulas). pmc.ncbi.nlm.nih.gov/articles/PMC4914842/
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-02. Spotted an error? See About.