Health & FitnessFormula-based · Runs in your browser

Lean Body Mass Calculator

Estimate lean body mass with Boer, James, and Hume adult equations or the Peters pediatric equation.

Preparing saved example…

Inputs

Enter the values you know. Optional fields may be left empty.

Local save controls below
Required
Required
Required
Required
years
Required
kg
Required
cm

Result

Updates as valid inputs change.

Calculated locally
Lean-body-mass equations are population estimates and may be inaccurate for children, pregnancy, edema, or unusual body composition.
Average adult estimate
Boer estimate
James estimate
Hume estimate
Peters child estimate
Lean mass percentage

Saved locally, explained clearly

Drafts, calculations, scenarios, and workflow progress stay in this browser unless you export them.

Opening local database…

Calculation steps

Follow what happened from the selected formula to the displayed answer.

Show substituted values and intermediate working
Calculate current inputs to see the working.
  1. 1

    Formula selected

    The calculator uses the following formula or method.

    Adult equations: Boer, James, and Hume use sex-specific weight and height coefficients; Peters estimates extracellular volume and multiplies it by 3.8.

  2. 2

    Values entered

    Your values are placed into the calculation.

    Enter values to see what is used in this step.

  3. 3

    Result calculated

    The formula or method produces the following result values.

    Results will appear after a successful calculation.

  4. 4

    Answer formatted

    Displayed values are rounded and formatted using each output’s configured precision.

Scenario comparison

Save working scenarios, then select two or three to compare. Formula versions and inputs remain visible.

No scenarios saved for this calculator yet.

Recent calculations

Successful calculations are retained locally according to your privacy settings.

No local history for this calculator yet.

Data and privacy

How it works

Boer, James, and Hume estimate lean body mass from height, weight, and sex-based coefficients. The calculator shows each result instead of hiding their spread behind one number.

Input query strings and outputs

Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.

Input query strings

9
  • ?mode= Equation group

    Choice · Required · Default: adult · Accepted values: adult, child

  • ?unitSystem= Units

    Choice · Required · Default: metric · Accepted values: metric, imperial

  • ?sex= Sex used by equation

    Choice · Required · Default: male · Accepted values: male, female

  • ?age= Age

    Number · Required · Default: 30

  • ?weightKg= Weight

    Number · Required · Default: 70 · Used when unitSystem = metric

  • ?heightCm= Height

    Number · Required · Default: 175 · Used when unitSystem = metric

  • ?weightLb= Weight

    Number · Required · Default: 154 · Used when unitSystem = imperial

  • ?feet= Height feet

    Number · Required · Default: 5 · Used when unitSystem = imperial

  • ?inches= Height inches

    Number · Required · Default: 9 · Used when unitSystem = imperial

Outputs

6
  • average Average adult estimate

    Text · Primary output

  • boer Boer estimate

    Text

  • james James estimate

    Text

  • hume Hume estimate

    Text

  • peters Peters child estimate

    Text

  • leanPercent Lean mass percentage

    Percentage

Pediatric mode

Peters first estimates extracellular volume and then derives lean body mass. Pediatric interpretation belongs with a qualified clinician.

Sources
Limitations
  • Lean-body-mass equations are population estimates and may be inaccurate for children, pregnancy, edema, or unusual body composition.
  • Health results are educational estimates, not a diagnosis or treatment recommendation. Individual circumstances may require a qualified clinician's assessment.