Lean Body Mass Calculator
Lean body mass is everything in your body that is not fat — muscle, bone, organs and water. Enter your details to estimate it with the Boer formula and see how it splits from your fat mass.
Lean Body Mass Calculator
Lean body mass is everything in your body that is not fat — muscle, bone, organs and water. Enter your details to estimate it with the Boer formula and see how it splits from your fat mass.
Used because the formula differs for men and women.
- Estimated fat mass
- 15.2 kg
- Lean mass as % of weight
- 78.9%
Lean body mass is everything that is not fat — muscle, bone, organs and water. Estimated with the Boer formula.
This is an educational estimate, not medical advice. Consult a qualified professional.
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How lean body mass is estimated
This calculator uses the Boer formula, a well-regarded equation derived for estimating lean mass in adults. It is based on weight, height and sex:
For men: LBM = (0.407 × weight kg) + (0.267 × height cm) − 19.2. For women: LBM = (0.252 × weight kg) + (0.473 × height cm) − 48.3. Your estimated fat mass is then simply your total weight minus your lean body mass. The split bar above shows the two side by side.
Why lean body mass matters
Lean mass — particularly muscle — drives your metabolism, strength and physical resilience. People with more lean mass burn more calories at rest, manage blood sugar better, and tend to recover and age more robustly. Preserving lean mass is especially important during weight loss: a sharp, crash diet can strip away muscle along with fat, which is one reason adequate protein and resistance training are so widely recommended.
Tracking LBM alongside body weight tells you whether changes on the scale are coming from fat or from muscle. Losing weight while keeping (or gaining) lean mass is the goal of a healthy body-recomposition plan.
Reading your result
The Boer formula gives a population estimate, not a direct measurement, and it does not "see" your actual muscle. Very lean, very muscular or very high-body-fat individuals will see less accurate figures. For precise lean-mass measurement, a DEXA scan or bioelectrical impedance analysis is needed. As with body fat, the most reliable use is to track the trend under consistent conditions rather than to treat a single number as exact.
Frequently asked questions
What is lean body mass?
Lean body mass is your total weight minus your fat mass — it includes muscle, bone, organs, connective tissue and body water. It is sometimes called fat-free mass.
Why is the Boer formula used?
The Boer formula is a validated equation for estimating lean mass from height, weight and sex, and is commonly used in clinical and fitness settings where a direct scan is not available.
How can I increase my lean body mass?
Regular resistance training combined with adequate protein intake and sufficient sleep is the most effective way to build and preserve lean mass, especially while losing fat.
Sources & references
Not medical advice. This result is an educational estimate from HealthyLifeStyles (Trusted Wellness), based on population formulas — not a diagnosis or treatment. Always consult a qualified healthcare professional about your health.
https://www.healthylifestyles.com/tools/lean-body-mass-calculator