Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Health, Fitness & Wellness
Lean Body Mass Calculator from Weight and Body Fat
LBM = weight × (1 − body fat % ÷ 100).
Split scale weight into lean mass and fat mass from body-fat %. Estimates only—not a diagnosis or prescription.
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Inputs
80350
360
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Recommendations
Tailored to your live inputs and result—guidance only, not professional advice.
- Interpret
Treat this as a planning estimate
Primary result: Lean body mass = 144.0 lbs. Re-run with optimistic and pessimistic inputs to understand the range—not just a single point.
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Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
Weight (lbs)
The “Weight (lbs)” value used in this tool’s formula. Adjust it to see results update live.
Body fat (%)
The “Body fat (%)” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
Split scale weight into lean mass and fat mass from body-fat %. Estimates only—not a diagnosis or prescription. LBM = weight × (1 − body fat % ÷ 100). Example: 180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
LBM = weight × (1 − body fat % ÷ 100).
Example: 180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
When to use this Lean Body Mass
Common use cases
- Split scale weight into lean mass and fat mass from body-fat %.
- Sanity-check with this case: 180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
- The relationship is: LBM = weight × (1 − body fat % ÷ 100).
Localized examples
- Health, Fitness & Wellness: the example on this page uses the same formula as the widget.
What you get
- Fields: Weight (lbs), Body fat (%)
- LBM = weight × (1 − body fat % ÷ 100).
- Example on the page: 180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
How to Calculate Lean Body Mass Step-by-Step
- 1Enter Weight (lbs), Body fat (%). Use the values you have, not a catalog average, unless that is all you know.
- 2LBM = weight × (1 − body fat % ÷ 100).
- 3Worked case: 180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
- 4If this number would change a drug, a diet, or a return-to-play call, take it to a clinician. The page never examined you.
Governing formula
LBM = weight × (1 − body fat % ÷ 100).
180 lb at 20% fat → 144 lb lean mass, 36 lb fat.
Example: set Weight (lbs) = 180, Body fat (%) = 20, then read the result.
Variable definitions
- weightLbs
Weight (lbs)
The “Weight (lbs)” field. Default 180; typical range 80–350.
- bodyFatPct
Body fat (%)
The “Body fat (%)” field. Default 20; typical range 3–60.
- The formula (LBM = weight × (1 − body fat % ÷ 100).) does not see labs, medications, sleep, or injury history. A clinician does.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
LBM = weight × (1 − body fat % ÷ 100).
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Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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