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General MedicineBSA

Body Surface Area (BSA) Calculator

Calculate estimated body surface area from height and weight using the Mosteller, Du Bois, or Haycock formula.

Content updated: View sources

QuickMedCalc is developed and maintained by an independent developer. Medical content is not independently reviewed by a physician.

Formula and medical content are based on the references listed on this page. See sources, About, and Sources and Review Process.

Input

Use the height or length value required for the applicable calculation. Total inches remains available when an external workflow provides inches directly.

Enter the weight basis required by the applicable rule. This calculator does not decide whether actual, ideal, adjusted, capped, or another weight should be used.

Select the formula required by the applicable drug label, protocol, study, institution, or clinical system. No formula is assumed.

These limits are data-entry guards, not healthy ranges, validated formula domains, or proof that a selected formula is appropriate.

Selected formula BSA

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No normal/abnormal category assigned

Formula detail

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No drug dose or BSA cap calculated

Selected formula: —

Normalized inputs: —

Calculations retain the full normalized height and weight. The primary result displays two decimal places and the detail displays four; neither display defines the precision or rounding required by a drug or protocol.

About

Body surface area (BSA) is an area estimate calculated from height and weight. The three formulas on this page were published as height-weight estimates; they do not directly measure body surface area or body composition. [1, 2, 3, 5]

This page runs only the formula selected by the user. It does not choose a formula, define a normal range, diagnose a condition, or generate a medication dose or treatment recommendation.

Formula

Mosteller: BSA (m²) = √[height (cm) × weight (kg) / 3600] [1]
Du Bois & Du Bois: BSA (m²) = 0.007184 × height (cm)^0.725 × weight (kg)^0.425 [2]
Haycock: BSA (m²) = 0.024265 × weight (kg)^0.5378 × height (cm)^0.3964 [3]
Exact input conversions: 1 in = 2.54 cm; 1 lb = 0.45359237 kg

Interpretation

Selected-formula estimate

The result is only the arithmetic output of the selected height-weight equation. It is not a direct surface measurement. [1, 2, 3]

No universal normal range

This calculator does not output Low, Normal, or High. The 1.73 m² kidney indexing convention is not a healthy or ideal BSA target.

Formula choice can matter

Du Bois was derived from a very small source sample; Haycock included measurements from premature infants through adults. Formula differences can become more apparent in children, obesity, and unusual body sizes, without making one equation universally best. [3, 4, 5]

Not a medication dose

The medication, indication, protocol, mg/m² value, cycle, organ-function and toxicity adjustments, cap, and rounding rule are not selected here. [6]

Not an eGFR or burn conversion

This page does not de-index eGFR, calculate burn total body surface area, or calculate burn-resuscitation volume. [7, 8]

Formula comparison examples

170 cm / 70 kg

  • Mosteller: 1.8181 m² → 1.82
  • Du Bois: 1.8097 m² → 1.81
  • Haycock: 1.8257 m² → 1.83

100 cm / 20 kg

  • Mosteller: 0.7454 m²
  • Du Bois: 0.7233 m²
  • Haycock: 0.7542 m²

60 cm / 5 kg

  • Mosteller: 0.2887 m²
  • Du Bois: 0.2771 m²
  • Haycock: 0.2922 m²

The same inputs produce different results because the formulas differ. These are arithmetic examples, not normal ranges. The calculator does not average the results or choose a “best” formula.

Formula origin and evidence limits

The Du Bois equation is commonly traced to nine subjects. Haycock used geometric surface measurements in 81 participants ranging from premature infants to adults. Mosteller's practical advantage is its simple square-root form, not proof that it is the most accurate equation in every population. No formula is presented here as a universal gold standard. [1, 2, 3, 5]

Body-size extremes and obesity

In Verbraecken's adult comparison, formulas were highly correlated, while Du Bois estimates could be lower than other equations in adults with obesity. Redlarski found that differences among formulas may widen for unusual body sizes and in children. These studies do not establish one fixed error for every person or population. [4, 5]

Oncology and medication boundaries

ASCO's 2021 update addresses systemic antineoplastic treatment in adults with obesity and supports full weight-based cytotoxic chemotherapy dosing when otherwise appropriate. It does not mean every medication uses BSA, name one of this page's equations as a universal choice, or authorize this calculator to determine a total dose, cap, or toxicity adjustment. [6]

BSA and indexed eGFR

absolute eGFR ≈ indexed eGFR × BSA / 1.73

This is a de-indexing relationship. This page does not collect eGFR or generate a medication dose. Near a dosing threshold, interpretation must follow the specific medicine information and applicable clinical rule. [7, 8]

BSA, BMI, and burn TBSA are different

  • BSA: an estimated area in m².
  • BMI: a weight-for-height screening ratio in kg/m².
  • Burn TBSA: the percentage of body area affected by qualifying burns.

Related calculators serve different purposes

These three outputs are not interchangeable.

References

  1. Mosteller RD. Simplified calculation of body-surface area. New England Journal of Medicine. 1987;317(17):1098. PMID 3657876. DOI 10.1056/NEJM198710223171717.
  2. Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Archives of Internal Medicine. 1916;17:863–871. Reprinted in Nutrition. 1989;5(5):303–311. PMID 2520314.
  3. Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: a height-weight formula validated in infants, children, and adults. Journal of Pediatrics. 1978;93(1):62–66. PMID 650346. DOI 10.1016/S0022-3476(78)80601-5.
  4. Verbraecken J, Van de Heyning P, De Backer W, Van Gaal L. Body surface area in normal-weight, overweight, and obese adults: a comparison study. Metabolism. 2006;55(4):515–524. PMID 16546483. DOI 10.1016/j.metabol.2005.11.004.
  5. Redlarski G, Palkowski A, Krawczuk M. Body surface area formulae: an alarming ambiguity. Scientific Reports. 2016;6:27966. PMID 27323883. PMCID PMC4914842. DOI 10.1038/srep27966.
  6. Griggs JJ, et al. Appropriate Systemic Therapy Dosing for Obese Adult Patients With Cancer: ASCO Guideline Update. Journal of Clinical Oncology. 2021;39(18):2037–2048. PMID 33939491. DOI 10.1200/JCO.21.00471.
  7. NIDDK. Determining Drug Dosing in Adults with Chronic Kidney Disease. Official clinical resource. Last reviewed October 2024.
  8. Mohamed AAA, van Londen M, Stevens J, Heerspink HJL, Gansevoort RT. Indexing for Body Surface Area when Assessing Kidney Function. Nephrology Dialysis Transplantation. 2026. PMID 41860431. DOI 10.1093/ndt/gfag063.

Related Calculators

BMI

Calculate adult BMI from metric or US customary inputs, view the CDC adult screening category, and see the formula-derived weight span for BMI 18.5–24.9 at the entered height with non-diagnostic interpretation limits.

eGFR

Estimate adult race-free indexed glomerular filtration rate (eGFR) with 2021 CKD-EPI creatinine, 2012 cystatin C, or 2021 combined equations.

Adult Burn TBSA

Estimate qualifying adult burn total body surface area with classic Rule of Nines anterior and posterior segments.

Disclaimer

Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.