Lean Body Mass Calculator

What this calculator does

Every input on this lean body mass calculator maps to a real decision, so the output is something you can act on immediately, not a rough ballpark you'll have to double-check elsewhere.

Lean body mass is your body weight minus fat.

Common mistakes

• Assuming BF is exact
• Ignoring hydration
• Comparing across scales

When to use it

Use to target protein intake and track muscle.

Pro tips for the Lean Body Mass Calculator

• Save your favorite scenarios by clicking the star icon — they're stored locally, no account needed.
• For big decisions, run best-case, expected, and worst-case scenarios and compare the breakdowns side by side.
• Copy the result to paste it directly into email, Notion, or a spreadsheet cell.

Frequently asked questions

›LBM vs FFM?

Very close; FFM excludes essential fat too.

›Protein by LBM?

2–2.5 g/kg LBM common target.

›Grow LBM?

Progressive resistance training + protein.

›LBM plateau?

Diet break may help.

›Water weight?

Affects total mass, not LBM much.

›Where does the formula come from?

The formula shown in the "How it works" section is the same one you'll find in standard health & fitness references — no proprietary tweaks or hidden weightings.

›Does the Lean Body Mass Calculator store the numbers I enter?

No. All math runs locally in your browser — nothing is sent to a server, and closing the tab discards the inputs unless you save them to favorites.

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