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General MedicineAnthropometry

BSA & BMI Calculator with Adult Anthropometry Models

Calculate adult body surface area (BSA) and BMI from height and weight. Choose Mosteller, Du Bois & Du Bois, or Haycock for BSA, then add optional measurements only when you want additional anthropometry models.

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

Use height and weight to calculate adult BSA and BMI.Choose Mosteller, Du Bois & Du Bois, or Haycock for the primary BSA result. Add waist, hip, age, and model-specific inputs only when you want additional anthropometry results; missing values are never inferred.
Core BSA and BMI inputs

Changing systems clears the record instead of relabeling existing numbers.

Height and weight calculate BMI; add an explicit BSA formula to calculate BSA.

Height and weight calculate BMI and supply the selected BSA formula.

Select the primary published formula explicitly. The result also compares all three on the same inputs without ranking them.

Additional anthropometry measurements

Add only the measurements required for the additional models you want. Waist and hip values still require explicit landmark protocols.

Used only with the protocol selected below. Do not substitute navel, narrowest-waist, midpoint, or iliac-crest sites silently.

Required when a waist is entered. This choice controls source-comparability labels, not the raw arithmetic formula.

Used by WHR and BAI; it is never substituted for waist.

Required when hip circumference is entered.

Optional. Used only by Boer FFM, adult RFM, and an eligible ABSI reference row; it is never inferred.

Adult RFM accepts 20–85. ABSI NHANES reference rows cover ages 18–84 plus the published 85+ sample row. Age does not enter raw ABSI or RFM arithmetic.

Measurement-quality note: Measurements collected during the same assessment are usually more suitable for comparing model outputs. This guidance does not block BMI, BSA, or other supported calculations.

Core results

Enter height and weight for BMI, select a BSA formula when you also want body surface area, then calculate. Additional measurements remain optional.

About

Use standing height and body weight to calculate adult body surface area (BSA) and BMI. BSA is an estimate in square meters; choose Mosteller, Du Bois & Du Bois, or Haycock explicitly so the selected published equation remains visible. [2, 3, 4]

Add waist, hip, age, and a published male/female model branch only when you want the separately named FFM/FFMI, WHtR, WHR, BRI, ABSI, BAI, or RFM outputs. Missing inputs remain missing, and the results are never combined into a proprietary score, diagnosis, or treatment recommendation.

Waist provenance is retained because the WHO/NICE midpoint and NHANES iliac-crest landmarks are different. Raw arithmetic can sometimes be calculated from another or unknown site, but source/reference comparability is then withheld. [7, 8]

Formula

Mosteller BSA: √[(height cm × weight kg) / 3600]. [2]
Du Bois & Du Bois BSA: 0.007184 × height cm0.725 × weight kg0.425. [3]
Haycock BSA: 0.024265 × weight kg0.5378 × height cm0.3964. [4]
BMI and additional models: BMI and Boer FFM/FFMI each call their existing validated runtime; the published coefficient remains explicit. [1, 5]
WHtR and WHR are ratios. BRI, ABSI, and RFM call their original model runtimes using the entered waist value while separately reporting whether the recorded waist protocol matches the model/reference source. [6, 7, 9, 10, 13]
BAI uses standing height and hip circumference; WHR uses waist and hip. A hip value is never substituted for waist, and neither result is a direct scan or diagnosis. [7, 12]

Interpretation

Measurement-protocol matrix

Recorded siteSource-matched contextOther models
WHO/NICE midpoint waistWHtR and WHO WHR contextBRI, ABSI, and RFM may return raw arithmetic, labeled arithmetic-only rather than NHANES-comparable.
NHANES iliac-crest waistThomas BRI, original ABSI/NHANES, and adult RFM contextWHtR and WHR may return raw ratios, but no WHO/NICE midpoint comparability is claimed.
Other / unknown waistNo named source comparisonOnly raw arithmetic that the existing model runtime can safely support.

WHO measures waist at the midpoint between the lowest palpable rib and iliac crest and hip at the widest buttock circumference. NHANES marks just above the uppermost lateral border of the right ilium. The workspace never converts one landmark into another. [7, 8]

Interpret each model separately

BSA is an estimated surface area and this page does not define a universal normal BSA range. BMI retains the CDC adult screening category; FFM/FFMI, BRI, ABSI, BAI, and RFM remain model estimates or indices rather than direct body-composition measurements. WHtR and WHR keep their source-specific population context without producing an individualized disease probability. [1, 2, 3, 4, 6, 7, 9, 12, 13]

Body Surface Area (BSA)

BSA estimates body surface area from standing height and body weight and reports square meters (m²). It is a formula-derived estimate, not a direct measurement and not a diagnosis.

How BSA is calculated

After you explicitly choose a primary formula, the workspace passes the same normalized height and weight to the existing Mosteller, Du Bois & Du Bois, and Haycock runtimes. The selected formula remains the primary result, while the comparison shows how the three published equations differ on the same inputs; it does not average or rank them. [2, 3, 4]

Is there a normal BSA range?

This page does not define a universal individualized “normal BSA” range or label a BSA as healthy or unhealthy. Population descriptions are not a substitute for a person-specific clinical protocol, and this calculator does not turn BSA into a medication dose or treatment recommendation.

BSA vs BMI

Both can be calculated from height and weight, but they answer different questions. BMI is a weight-for-height screening index reported in kg/m²; BSA is an estimated body surface area reported in m². Neither result replaces the other. [1, 2, 3, 4]

Additional anthropometry models

ModelInputs requiredOutputKey limitation
Boer FFM / FFMIHeight, weight, published male/female branchEstimated FFM and FFMINot measured lean tissue
WHtRHeight, waist, waist protocolWaist-to-height ratioReference comparability depends on waist landmark
WHRWaist, hip, both protocolsWaist-to-hip ratioNo individual disease probability
BRIHeight, waist, waist protocolGeometric indexNot measured body fat or visceral adipose tissue
ABSIHeight, weight, waist, protocol; age/branch for referenceRaw ABSI and optional NHANES z-scoreResearch index, not mortality probability
BAIHeight, hip, hip protocolBody Adiposity IndexNot a direct body-fat measurement
Adult RFMAge 20–85, height, waist, protocol, published branchRegression estimate (%)Not DXA/BIA or a universal category

Privacy and boundaries

The record is ephemeral browser state. Measurements and results are not added to the URL, browser storage, an account, or a QuickMedCalc backend. Reloading starts with a blank record. No model vote, overall body score, diagnosis, target, treatment, or tracking history is created.

References

  1. CDC. Adult BMI Calculator and Adult BMI Categories. Adult BMI is a screening measure for people age 20 and older.
  2. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. PMID 3657876.
  3. Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;17:863–871.
  4. Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area. J Pediatr. 1978;93(1):62–66. PMID 650346.
  5. Boer P. Estimated lean body mass as an index for normalization of body fluid volumes in humans. Am J Physiol. 1984;247:F632–F636. PMID 6496691.
  6. NICE. Overweight and obesity management (NG246): identifying and assessing overweight, obesity and central adiposity. Current recommendations and applicability limits.
  7. World Health Organization. Waist Circumference and Waist-Hip Ratio: Report of a WHO Expert Consultation. Published 2011. ISBN 9789241501491.
  8. CDC/NCHS. National Health and Nutrition Examination Survey: 2021 Anthropometry Procedures Manual.
  9. Thomas DM, Bredlau C, Bosy-Westphal A, et al. Relationships between body roundness with body fat and visceral adipose tissue emerging from a new geometrical model. Obesity. 2013;21:2264–2271. PMID 23519954.
  10. Krakauer NY, Krakauer JC. A new body shape index predicts mortality hazard independently of body mass index. PLoS One. 2012;7:e39504. PMID 22815707.
  11. Krakauer NY, Krakauer JC. Supplementary Table S1: NHANES 1999–2004 age- and sex-specific ABSI reference means and standard deviations.
  12. Bergman RN, Stefanovski D, Buchanan TA, et al. A Better Index of Body Adiposity. Obesity. 2011;19:1083–1089. PMID 21372804.
  13. Woolcott OO, Bergman RN. Relative fat mass as a new estimator of whole-body fat percentage. Sci Rep. 2018;8:10980. PMID 30030479.
  14. NIST. SI Units—Length. The international inch is exactly 2.54 centimeters.

FAQ

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Disclaimer

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