Lean Body Mass Calculator

Estimate adult lean body mass with the sex-specific Boer equations, or calculate fat-free mass from a measured body fat percentage.

Calculation inputs

Choose a method that matches your data

1
Boer needs height, weight and equation sex
Use adult standing measurements and the coefficients in the original model.
2
Body-fat mode is a separate calculation
If a documented fat percentage is available, derive the fat-free remainder from total weight.
3
Do not equate the number with muscle
Water, bone, organs and connective tissue also contribute. Medication dosing requires a clinician.

Measurement and method sources are linked below. Illustrations explain the workflow; they do not supply measurement data.

Explore the calculation model

Estimated mass components

Calculation results

Lean body mass estimate58.05 kgBoer equation · male coefficients

Body weight75 kg

Fat remainder16.95 kg

Lean fraction77.4%

Step-by-step solution

Choose the formula
$Boer male: LBM (kg) = 0.407 × weight (kg) + 0.267 × height (cm) − 19.2$
Substitute your measurements
$0.407 × 75 + 0.267 × 175 − 19.2$
Calculate in order
$30.525 + 46.725 − 19.2$
Write the result
$58.05 kg$

Representative adult mannequin with body-composition measuring equipment — Representative illustration · not a scan, patient measurement or image to scale.

1
Use the correct input units
Weight 75 kg · height 175 cm
2
Apply the selected Boer equation
0.407 × 75 + 0.267 × 175 − 19.2
3
Check the estimated components
58.05 kg + 16.95 kg = 75 kg

Water, organs, bone and connective tissue contribute to the estimate. It must not be read as kilograms of skeletal muscle.

Educational adult body-composition estimate. Do not use this result to choose or adjust a medication dose.

This is an anthropometric estimate, not measured skeletal muscle. Prediction errors increase outside the population used to develop an equation.

Measurements & calculation details

58.05 kg

Quantity	Value
Method	Boer adult equation
Body weight	75 kg
Lean / fat-free estimate	58.05 kg
Fat remainder	16.95 kg

Try a worked example

Choose an example to load its measurements into the calculator. Each result uses the same calculation engine as your own inputs. Back to your calculation

Understand the calculation

Concept & meaning

Lean body mass is a body-size descriptor, not a synonym for skeletal muscle. Boer predicts it from weight, height and sex. In the separate body-fat mode, the calculator derives fat-free mass by subtracting the estimated fat component from total weight.

Formula & special cases

Boer uses W in kilograms and H in centimetres: male = 0.407W + 0.267H − 19.2; female = 0.252W + 0.473H − 48.3. The body-fat mode uses W × (1 − p/100). These are distinct methods and can give different estimates.

Scope & limitations

LBM and fat-free mass have technical definitional differences, including the treatment of essential lipids. The outputs here are method-labeled estimates, not interchangeable measured quantities. Equations can fail at unusual body proportions; nonphysical results are rejected instead of being clamped.

Boer male: LBM (kg) = 0.407 × weight (kg) + 0.267 × height (cm) − 19.2

Result from your current inputs

Lean body mass estimate: 58.05 kg

Frequently asked questions

Does this calculate how much muscle I have?

No. The non-fat component also includes water, organs, connective tissue and bone. Skeletal muscle requires a separate assessment.

Why does sex change the Boer result?

The original equation provides different coefficients for the two sex groups used to develop it. Height and weight alone do not individualize the model beyond those coefficients.

Which mode should I use?

Boer is a prediction from simple measurements. Body-fat mode derives fat-free mass from your entered body-fat percentage. Select the method that matches your available data and interpret its limitations.

Can I use the result for drug dosing?

No. Drug-specific body-size descriptors, caps and clinical factors must be assessed by a qualified prescriber or pharmacist. This calculator is educational.

Show all questions (5 more)Show fewer questions

What does the Lean Body Mass calculate?

Estimate adult lean body mass with the sex-specific Boer equations, or calculate fat-free mass from a measured body fat percentage.

Which values should I enter?

Use the labeled fields above. Values outside the supported range clear the result and show an explanation.

What formula does this calculator use?

Boer male: 0.407W + 0.267H − 19.2; female: 0.252W + 0.473H − 48.3; W in kg, H in cm

Why might my result differ from another source?

Results can differ because measurement methods, rounding and assumptions vary. This calculator is an estimate and is not a medical diagnosis.

Does the result update automatically?

Yes. Inputs and presets update the result, teaching diagram and expandable steps together. Invalid input clears the previous result.

Equation coefficients and units

Calculation	Formula	Interpretation
Boer · male	0.407W + 0.267H − 19.2	W: kg; H: cm; result: kg
Boer · female	0.252W + 0.473H − 48.3	W: kg; H: cm; result: kg
Body-fat mode	W × (1 − p/100)	Fat-free mass; p is a percentage

Sources & References

Boer · 1984Original adult lean-body-mass prediction studyRead the reference

Published Boer coefficients · 2024Explicit male/female Boer coefficients · formula reference onlyRead the reference

References document the methods and their limitations; links and logos do not imply institutional endorsement or expert review.