James Formula Lean Mass Calculator
The 1976 James LBM equation with its quadratic weight term — and the high-BMI breakdown it is famous for.
James added a quadratic penalty so lean mass stops growing linearly with weight — physiologically sensible, but above roughly BMI 35 the parabola turns over and the formula starts predicting *less* lean mass as weight rises, which is why clinical software increasingly swaps it for Boer or Janmahasatian.
Formula
For general information only — not medical advice, a diagnosis or a treatment plan. Consult a qualified healthcare professional before making health, diet, medication or exercise decisions.
The 1976 James LBM equation with its quadratic weight term — and the high-BMI breakdown it is famous for. The James Formula Lean Mass Calculator is a free, private james formula tool — every result computes instantly in your browser with no sign-up and no data upload.
About James Formula Lean Mass Calculator
James added a quadratic penalty so lean mass stops growing linearly with weight — physiologically sensible, but above roughly BMI 35 the parabola turns over and the formula starts predicting *less* lean mass as weight rises, which is why clinical software increasingly swaps it for Boer or Janmahasatian. It applies M: 1.10W − 128(W/H)² · F: 1.07W − 148(W/H)² (H in cm). Use the James Formula Lean Mass 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 James Formula Lean Mass Calculator
- 1Enter your details in the James Formula Lean Mass 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 James Formula Lean Mass Calculator?
- ✓Instant james 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 (James WPT, Research on Obesity, HMSO 1976)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the James Formula Lean Mass Calculator work?+
James added a quadratic penalty so lean mass stops growing linearly with weight — physiologically sensible, but above roughly BMI 35 the parabola turns over and the formula starts predicting *less* lean mass as weight rises, which is why clinical software increasingly swaps it for Boer or Janmahasatian. The calculation uses the formula: M: 1.10W − 128(W/H)² · F: 1.07W − 148(W/H)² (H in cm). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the James Formula Lean Mass Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources, including James WPT, Research on Obesity, HMSO 1976; Green B & Duffull S, Clin Pharmacol Ther 2002 — critique at high BMI. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the James Formula Lean Mass 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 tool is for general information only and is not medical advice. Always consult a qualified healthcare professional before making health decisions.
What can I use the James Formula Lean Mass Calculator for?+
It's commonly used for james formula, james lean body mass, lbm equation. The 1976 James LBM equation with its quadratic weight term — and the high-BMI breakdown it is famous for.
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