Estimate your lean body mass and fat mass using the Boer formula.
Calculated instantly in your browser.
How is lean body mass calculated?
Using the Boer formula — men: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2; women: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3. Lean body mass is everything that is not fat. For example, an 80 kg man who is 180 cm tall has an estimated lean body mass of about 61.4 kg.
Understanding your result
Lean body mass is everything that is not fat. Estimating it helps set nutrition targets and track whether weight change is muscle or fat. Formula estimates are approximations — methods like DEXA are more precise.
Formula and method
Boer formula — men: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2; women: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3.
Assumptions and limitations
The Boer formula gives an approximation from weight, height and sex only, so it is a general estimate rather than medical advice. It cannot see your actual muscle, bone or fat and may be less accurate at the extremes of body composition. Methods such as DEXA measure lean mass more precisely.
Worked example
A 80 kg man who is 180 cm tall has an estimated lean body mass of about 61.4 kg.
How to use this tool
- Enter your weight and height with units.
- Select your sex.
- Read your lean body mass and fat mass.
Common mistakes to avoid
- Entering weight and height in mismatched units.
- Treating the estimate as exact — it varies by individual.
About the Lean Body Mass Calculator
The Lean Body Mass Calculator estimates how much of your body weight is lean tissue — muscle, bone, organs and water — versus stored fat, using the Boer formula from your weight, height and sex.
Who should use this tool
Athletes, dieters and anyone tracking body composition rather than just weight.
Benefits
- Lean mass and fat mass in kg and lb.
- Estimated body-fat percentage.
- Works in metric or imperial units.
- Useful for setting protein and calorie targets.
Practical use cases
- Tracking muscle retention while dieting.
- Setting protein intake from lean mass.
- Comparing body composition over time.
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Frequently asked questions
What is lean body mass?
It is your total weight minus body fat — muscle, bone, organs, connective tissue and body water.
How accurate is the Boer formula?
It gives a reasonable estimate for most adults but cannot match direct measurement methods such as DEXA or hydrostatic weighing.
Can I use lean body mass to track progress?
Estimated lean body mass can help you see whether a change in weight is mostly lean tissue or fat, which weight alone cannot show. Because it is a formula-based approximation, focus on the trend across repeated measurements under similar conditions rather than any single figure.