Health & Fitness
Lean Body Mass Calculator
Compare the sex-coded Boer estimate with body-fat-based lean mass, calculate an explicit uncertainty interval, and inspect method sensitivity. The page includes formula notes, examples, limitations, FAQs, and an exportable record.
Boer male lean-body-mass estimate-
Boer female lean-body-mass estimate-
Selected Boer estimate-
Lean mass from entered body-fat estimate-
Lean mass at higher body-fat bound-
Lean mass at lower body-fat bound-
Boer minus body-fat-based estimate-
Decision view
Lean-body-mass estimate range
Lean-body-mass estimate rangeThe selected Boer result and body-fat-based interval are displayed separately.
Lean-mass methods across body-fat scenariosEntered body-fat percentage changes across the exact scenarios; the circumference-independent Boer estimate and body-fat-derived interval remain separately labeled.
Exact scenario comparisonIndependent body-fat estimate (%) changes while all other entered assumptions remain constant.
| Independent body-fat estimate (%) | Boer male lean-body-mass estimate | Boer female lean-body-mass estimate | Selected Boer estimate | Lean mass from entered body-fat estimate | Lean mass at higher body-fat bound | Lean mass at lower body-fat bound | Boer minus body-fat-based estimate |
|---|
Period-by-period detail
Lean-mass method reconciliation
How to use Lean Body Mass Calculator
- Measure body weight and height consistently.
- Select the equation sex code used by the displayed Boer formula.
- Enter an independently obtained body-fat estimate and its plausible error.
- Compare methods and use the interval rather than treating either result as exact.
Calculator guide
Understanding Lean Body Mass Calculator
Lean body mass is body weight excluding estimated fat mass. This page compares a height-and-weight equation with a body-fat-based calculation and makes the entered measurement uncertainty visible instead of presenting one value as a direct measurement.
Calculation method
How the calculation works
Calculate the sex-coded Boer estimate and an independent body-fat-based estimate, including an explicit measurement-error range. The selected Boer equation uses entered height and weight. The independent method multiplies weight by one minus body-fat percentage; the error allowance raises and lowers body-fat percentage to create lean-mass bounds.
Method comparison
Choose the estimate for the actual decision
Different uses require different validation and professional oversight.
Worked situations
Practical examples
- A three-point body-fat error creates different upper and lower lean-mass estimates.
- The Boer and body-fat methods can disagree because they use different predictors.
- Rapid weight change from fluid can move calculated lean mass without changing tissue mass.
Better inputs
Useful tips
- Use the same scale and measurement conditions over time.
- Record the body-fat method and device with the result.
- Use clinical or sports-professional interpretation when the result affects care or performance decisions.
Before relying on the result
Limitations and common mistakes
- Neither method directly measures lean tissue.
- Equations can be inaccurate with unusual height, age, muscularity, edema, pregnancy, or illness.
- Body-fat error is entered as symmetric percentage points even though real error may not be symmetric.
Reference
Key terms
- Lean body mass
- Body mass other than estimated fat mass, including water, organs, bone, and muscle.
- Boer equation
- Population-derived height-and-weight equation used here with a selected sex code.
- Body-fat estimate
- Entered percentage used to calculate an independent lean-mass reference.
- Measurement interval
- Lean-mass range created by the entered body-fat error allowance.
Important note
Calculated from the entered measurements using the displayed method. It is a general reference and does not replace diagnosis or individualized professional guidance.
Frequently asked questions
Is lean body mass the same as muscle mass?
No. Lean mass includes water, organs, bone, and other nonfat tissue.
Why do the two estimates differ?
One is predicted from height and weight; the other depends directly on the entered body-fat estimate.
Which sex code should be selected?
Select only the equation variant appropriate to the intended protocol; the page does not determine that choice.
Can the interval be treated as a confidence interval?
No. It is a deterministic range from the entered error allowance, not a statistical confidence interval.