Boyd BSA Calculator
The weight-self-correcting 1935 BSA formula used by some cardiac-index and paediatric references.
Boyd's quirk is the weight exponent that itself shrinks as weight grows — an early recognition that surface area doesn't scale with a fixed power of mass. Some echocardiography labs and paediatric cardiology references still normalise to Boyd; know which formula your lab uses before comparing.
Formula
Reference aid for healthcare professionals only. Every result must be independently verified before clinical use. Never use this tool for self-medication or to replace clinical judgement.
The weight-self-correcting 1935 BSA formula used by some cardiac-index and paediatric references. The Boyd BSA Calculator is a free, private boyd formula tool — every result computes instantly in your browser with no sign-up and no data upload.
About Boyd BSA Calculator
Boyd's quirk is the weight exponent that itself shrinks as weight grows — an early recognition that surface area doesn't scale with a fixed power of mass. It applies BSA = 0.0003207 × H^0.3 × Wg^(0.7285 − 0.0188·log₁₀Wg) (Wg in grams). Use the Boyd BSA Calculator to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Boyd BSA Calculator
- 1Enter your details in the Boyd BSA Calculator input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Boyd BSA Calculator?
- ✓Instant boyd formula result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Boyd E, The Growth of the Surface Area of the Human Body, 1935)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Boyd BSA Calculator work?+
Boyd's quirk is the weight exponent that itself shrinks as weight grows — an early recognition that surface area doesn't scale with a fixed power of mass. The calculation uses the formula: BSA = 0.0003207 × H^0.3 × Wg^(0.7285 − 0.0188·log₁₀Wg) (Wg in grams). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Boyd BSA Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources: Boyd E, The Growth of the Surface Area of the Human Body, 1935. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Boyd BSA Calculator free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This is a reference aid for healthcare professionals and must be independently verified. It is not for self-diagnosis or self-medication.
What can I use the Boyd BSA Calculator for?+
It's commonly used for boyd formula, bsa boyd, body surface area boyd. The weight-self-correcting 1935 BSA formula used by some cardiac-index and paediatric references.
Related Health tools
Adult BMI Calculator (WHO)
Body-mass index for adults with the WHO reference bands shown neutrally, plus the substituted formula step by step.
● LiveBMI Calculator (lb & inches)
US-style BMI from pounds and inches using the ×703 conversion, with CDC adult reference ranges.
● LiveBMI Calculator for Women
BMI with reference context written for women — what the index can and cannot say about female body composition.
● Live