Body Surface Area (BSA) Calculator
Professional, accessible BSA calculator with metric and imperial units. Supports Mosteller, Du Bois & Du Bois, Haycock, Gehan & George, and Boyd formulas.
Enter standing height. Typical range 30–272 cm (12–107 in).
Bring forward decimal precision from scales for best accuracy.
How to Use this Calculator
Enter your height and weight, choose a unit system, and select the clinical formula you prefer. The calculator normalizes inputs internally to metric units and updates instantly whenever you hit Calculate or change an input.
The formula comparison ensures you can review the Mosteller result alongside Du Bois & Du Bois, Haycock, Gehan & George, and Boyd values so you can pick the approach used in your setting.
Methodology
The calculator converts imperial inputs to centimeters and kilograms, then applies the chosen α–β exponent formula. Rounding is applied only for display; internal calculations keep full double-precision accuracy.
- Mosteller is fast and widely used for chemotherapy dosing and clinical trials.
- Du Bois & Du Bois and Haycock offer slightly different exponent weights for height and weight.
- Gehan & George as well as Boyd provide alternative exponent combinations derived from large datasets.
The shared inputs update the URL automatically, letting you bookmark or share the exact scenario if needed.
Authoritative sources
These formulas come from peer-reviewed, clinical references:
- Mosteller RD. Simplified calculation of body surface area. N Engl J Med. 1987;317(17):1098. DOI: 10.1056/NEJM198710223171717.
- 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(6):863–871.
- Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: A height-weight formula validated in infants, children, and adults. J Pediatr. 1978;93(1):62–66.
- Gehan EA, George SL. Estimation of human body surface area from height and weight. Cancer Chemother Rep. 1970;54(4):225–235.
- Boyd E. The growth of the surface area of the human body. University of Minnesota Press; 1935.
Tutti i calcoli si basano rigorosamente sulle formule e sui dati originali forniti da queste fonti.
Step-by-step example
Inputs: Height = 170 cm, Weight = 70 kg, Formula = Mosteller.
Mosteller formula:
$$\mathrm{BSA} = \sqrt{\frac{170 \times 70}{3600}} \approx 1.818\,\mathrm{m}^2$$
Rounded to two decimals: 1.82 m².
Frequently asked questions
What is Body Surface Area (BSA)?
BSA is the total external surface area of the human body. Clinical dosing, normalization of clearance, and fluid resuscitation often rely on this metric.
Which formula is best?
No single formula fits everyone. Mosteller is easy and precise, but some institutions prefer Du Bois & Du Bois, Haycock, Gehan & George, or Boyd based on protocol.
Do I need to switch to metric?
No. Use inches and pounds if that matches your measurement system; the calculator converts to centimeters and kilograms.
Is this tool suitable for pediatrics?
Yes. Haycock and Mosteller are widely used for infants and children, but always follow pediatric dosing guidelines.
Can I rely on it for chemotherapy dosing?
This calculator is educational. Use it to cross-check dosing but always confirm with official protocols.
How accurate is BSA?
Each equation is an estimate from reference populations. Human variation means these are tools, not definitive measurements.
Why do formulas differ?
Different datasets and statistical models produce minor variations. Compare values to understand the range.
Why this calculator is different
- Multiple peer-reviewed formulas side-by-side for transparent comparison.
- Mobile-first, keyboard-navigable layout that meets WCAG 2.1 AA.
- Live URL sharing so you can bookmark precise inputs.
- Clear validation, contextual help, and double-precision rounding controls.
- No tracking, no external assets beyond MathJax for formulas — optimized for Core Web Vitals.