What is estimated
Estimated lean body mass from one selected height-weight regression, with all three equations shown side by side.
Lean Body Mass Calculator
Estimated lean body mass
Enter your values, then calculate to see a verified result.
Reference range
How this result is calculated
A clear calculation path based on your inputs.
Inputs usedReview the information used for this result.
Full calculation and sourcesReview the equation, normalized inputs, assumptions, and version.
Versioned calculationFormula v1.0.0
Method
Choose Boer, James, or Hume; each formula is reported separately instead of averaging incompatible models.
Important boundary
Lean body mass is not skeletal muscle mass, and regression equations cannot replace DXA, CT, MRI, or another direct assessment.
Normalize measurementsConvert weight to kilograms and height to centimeters.
176.4 lb = 80 kg; 5 ft 10.9 in = 180 cmApply every equationUse the published sex-specific Boer, James, and Hume coefficients.
Each equation remains visible.Compare, do not averageUse the selected method and inspect the formula spread.
A wide spread signals method sensitivity.Interpretation
kg is the selected lean-body-mass estimate, not measured muscle mass.
The formula spread shows how much model choice changes this result.
Use the same equation and measurement conditions for trend comparisons.
Use this result
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Related calculators and resources
Body Fat CalculatorEstimate body-fat percentage with a separate circumference method.FFMI CalculatorScale fat-free mass to height after entering a body-fat estimate.Relative Fat Mass CalculatorEstimate adult body-fat percentage from height and waist.BMI CalculatorCompare the height-weight screening index.
Method and test recordFormula v1.0.0
- Recorded scope
- health-body-composition
- Publisher
- CalculatorGeek
- Recorded review date
- 2026-10-04
- Next source review
- 2027-10-04
- Definition fixtures
- 4 configured scenarios
- Published examples
- 4 shown below
Recorded method
Independently recompute every equation from normalized metric inputs and compare alternate-unit parity, selected-method routing, and out-of-domain warnings.
These records describe the published model and reference tests. A test-case count is not a certification of every possible input or an independent specialist review. Editorial policy
Known limitations
- Boer, James, and Hume were derived from different samples and can disagree materially.
- An equation can be implausible at unusual height-weight combinations.
- Hydration, edema, pregnancy, aging, illness, and atypical body composition are not modeled.
- Do not use this page to calculate medication or contrast dosing.
Method sources
- Boer (1984): Estimated lean body mass as an index for normalization of body fluid volumes
- Caruso et al. (2018): Boer versus James lean-body-weight formulas
- He et al. (2016): Limits of height-weight lean-body-mass formulas versus CT
Latest model update
2026-10-04 - Initial CalculatorGeek shared-system implementation with source-backed method, fixtures, content, and result journey.
Reference inputs and expected results
Up to 12 examples from the configured definition fixtures are shown. Expected values use the stated output units; invalid inputs are intended to be rejected.
| Case | Inputs | Expected result |
|---|---|---|
| Boer male reference | Primary equation: boer; Equation sex term: male; Body weight: 80 kg; Standing height: 180 cm | Selected lean body mass estimate: 61.42 kg; Boer estimate: 61.42 kg; James estimate: 62.716 kg; Hume estimate: 57.7866 kg; Highest-to-lowest formula spread: 4.9294 kg |
| imperial parity | Primary equation: boer; Equation sex term: male; Body weight: 176.36981 lb; Standing height: 70.866142 in | Selected lean body mass estimate: 61.42 kg (allowed numeric tolerance: 0.02) |
| female Hume route | Primary equation: hume; Equation sex term: female; Body weight: 60 kg; Standing height: 165 cm | Selected lean body mass estimate: 43.43955 kg (allowed numeric tolerance: 0.0001) |
| invalid weight | Primary equation: boer; Equation sex term: male; Body weight: 20 kg; Standing height: 180 cm | Reject invalid input: weight |
Report an issue with this tool. Include the page URL, units, expected answer, and steps to reproduce. Do not include sensitive personal information.
On this page
What the Lean Body Mass Calculator answers
Estimate lean body mass with the Boer, James, or Hume regression and compare the equations without hiding their disagreement.
Lean body mass includes water, organs, bone, connective tissue, and skeletal muscle; it is not a direct muscle measurement.
Start with the Health calculators hub when you need to choose a different body-measurement method.
How to use the Lean Body Mass Calculator
- Choose the equation you want to treat as primary.
- Select the coefficient set used by that published equation.
- Enter measured weight and standing height.
- Read the selected estimate together with the three-formula spread and limitations.
For a complementary body-measurement workflow, use the Body Fat Calculator. Estimate body-fat percentage with a separate circumference method.
Formula, variables and method
Boer: male 0.407W + 0.267H - 19.2; female 0.252W + 0.473H - 48.3.
James: male 1.1W - 128(W/H)^2; female 1.07W - 148(W/H)^2.
Hume: male 0.32810W + 0.33929H - 29.5336; female 0.29569W + 0.41813H - 43.2933. W is kilograms and H is centimeters.
To compare this method with a different input model, open the FFMI Calculator. Scale fat-free mass to height after entering a body-fat estimate.
Worked examples and boundary checks
80 kg and 180 cm
For the male coefficient set, Boer gives 61.42 kg, James 62.72 kg, and Hume 57.79 kg. Selecting Boer reports 61.4 kg while keeping the 4.9 kg highest-to-lowest spread visible.
Boundary check
If an equation produces a value near or above total body weight, treat it as an out-of-domain estimate rather than clipping it into a plausible-looking answer.
How to interpret the result
The primary number belongs to the selected equation. Formula disagreement is information, not an error to be averaged away.
- Boer, James, and Hume were derived from different samples and can disagree materially.
- An equation can be implausible at unusual height-weight combinations.
- Hydration, edema, pregnancy, aging, illness, and atypical body composition are not modeled.
- Do not use this page to calculate medication or contrast dosing.
For another relevant cross-check, continue with the Relative Fat Mass Calculator. Estimate adult body-fat percentage from height and waist.
Frequently asked questions
Is lean body mass the same as muscle mass?
No. Lean body mass includes muscle plus water, organs, bone, and other non-fat tissue.
Which equation should I choose?
Use the method required by your source or protocol. For general comparison, Boer is a common starting point, but no height-weight equation is a direct measurement.
Why do the three formulas disagree?
They were derived from different populations with different regression structures.
Can I use this result for a drug or contrast dose?
No. A clinician or pharmacist must select and verify the method required by the actual protocol.
How should I track change?
Repeat the same equation and measurement conditions; small changes can be formula and measurement noise.
Primary sources and evidence limits
- Boer (1984): Estimated lean body mass as an index for normalization of body fluid volumes
- Caruso et al. (2018): Boer versus James lean-body-weight formulas
- He et al. (2016): Limits of height-weight lean-body-mass formulas versus CT
Sources were checked 2026-10-04. They establish the published method or measurement context; they do not turn an anthropometric estimate into a diagnosis, direct body-composition measurement, or treatment recommendation.