Health Tools

Lean Mass Index Calculator

Estimate lean mass index from height and lean body mass, or from height, weight, and body fat percentage.

Updated April 13, 2026
Free online tool
Planning and research use

Why this page exists

Body-composition comparisons get easier when lean mass is expressed relative to height instead of being read only as a raw weight figure. This calculator helps visitors estimate lean mass index from lean body mass and height, or from weight and body fat percentage when lean mass is not already known.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Lean mass index calculator

Estimate lean mass index from lean body mass and height, or from weight and body fat percentage.

Result

20.97

Estimated lean mass index based on height and either lean body mass directly or weight and body fat percentage.

Lean mass index20.97

Lean mass used66.29 kg

Height used1.778 m

Reference noteGeneral body-composition estimate only

66.29 kg of lean mass at 1.778 meters tall gives a lean mass index near 20.97.
In body-fat mode, lean mass is estimated from body weight after subtracting the body fat percentage entered.
Use the output as a quick comparison-oriented body-composition estimate, not as a medical diagnosis or a complete health assessment.

This is a general body-composition estimate, not medical advice. Lean mass index can be useful for comparison, but it does not replace professional assessment of body composition or health.

Planning note

Last updated April 13, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Choose whether to start from lean body mass directly or from body weight and body fat percentage.

Enter height in imperial or metric units and the other measurements required for the mode selected.

The calculator estimates lean mass if needed, then divides lean mass by height in meters squared to estimate lean mass index.

Understanding your result

This is a general body-composition estimate, not medical advice. It can be useful for comparison and screening, but it does not replace professional assessment of body composition or health.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Estimate LMI from known lean body mass

Direct lean-mass input is helpful when lean body mass has already been estimated elsewhere and you only want the height-adjusted index.

Estimate LMI from body weight and body fat

If lean body mass is not known directly, the calculator can estimate it first from weight and body fat percentage.

Use it with other body-composition tools

Lean mass index often fits naturally beside lean-body-mass, body-fat, BMI, and BMI-Prime checks.

FAQ

Common questions

How is lean mass index calculated here?

The calculator divides lean mass in kilograms by height in meters squared. If you choose body-fat mode, it estimates lean mass first from body weight and body fat percentage.

Can I use height and body fat percentage without known lean mass?

Yes. The calculator can estimate lean mass from body weight and body fat percentage before calculating LMI.

Is lean mass index medical advice?

No. It is a general body-composition estimate and should not be treated as a diagnosis or a substitute for professional care.

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