Fat Mass Index (FMI) Calculator
Fat mass scaled to height² — FFMI's forgotten sibling that separates 'high BMI from muscle' vs 'from fat'.
FMI + FFMI literally add up to BMI — splitting it into its fat and lean components. Two people at BMI 28 might be FMI 9 / FFMI 19 or FMI 5 / FFMI 23: completely different bodies that BMI alone cannot distinguish. Reference bands here come from US DXA population data.
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.
Fat mass scaled to height² — FFMI's forgotten sibling that separates 'high BMI from muscle' vs 'from fat'. The Fat Mass Index (FMI) Calculator is a free, private fat mass index tool — every result computes instantly in your browser with no sign-up and no data upload.
About Fat Mass Index (FMI) Calculator
FMI + FFMI literally add up to BMI — splitting it into its fat and lean components. It applies FMI = fat mass ÷ height²; FFMI = fat-free mass ÷ height². Use the Fat Mass Index (FMI) 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 Fat Mass Index (FMI) Calculator
- 1Enter your details in the Fat Mass Index (FMI) 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 Fat Mass Index (FMI) Calculator?
- ✓Instant fat mass index 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 (Kelly TL et al., PLoS ONE 2009;4:e7038 — DXA reference values)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Fat Mass Index (FMI) Calculator work?+
FMI + FFMI literally add up to BMI — splitting it into its fat and lean components. The calculation uses the formula: FMI = fat mass ÷ height²; FFMI = fat-free mass ÷ height². Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Fat Mass Index (FMI) Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources: Kelly TL et al., PLoS ONE 2009;4:e7038 — DXA reference values. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Fat Mass Index (FMI) 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 Fat Mass Index (FMI) Calculator for?+
It's commonly used for fat mass index, fmi calculator, fmi ffmi. Fat mass scaled to height² — FFMI's forgotten sibling that separates 'high BMI from muscle' vs 'from fat'.
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