Lean Body Mass (LBM) is your weight minus the fat. It's the metric serious lifters track because it tells you whether bulks are adding muscle and cuts are sparing it. This calculator uses three classic formulas - Boer, James and Hume - and shows the average for a balanced estimate.
Boer (modern)
56.8 kg
James
57.5 kg
Hume
53.5 kg
Average LBM
55.9 kg
Of three formulas
Implied body fat
22.3%
16.1 kg fat
Body composition (estimated)
LBM formulas are regression estimates from population data - accurate within 2-3 kg for most people. For precise body composition consider a DEXA scan. Boer is the modern clinical standard.
لا يزال بعض المحتوى معروضًا بالإنجليزية.
Lean Body Mass (LBM) - your weight minus body fat - is the single best marker of training success for anyone focused on body composition. Body weight alone can mislead: gaining 5 kg of muscle while losing 5 kg of fat shows no scale change but is enormous progress. LBM tracks that progress directly. For lifters in cutting phases, maintaining LBM while losing weight means you're losing fat (not muscle). For lifters in bulking phases, rising LBM means the surplus is going to muscle, not fat.
This calculator combines three established LBM regression formulas - Boer (1984, the clinical standard), James (1976) and Hume (1971) - and shows the average. The three agree within 1-3 kg for most people, and the average is a robust estimate that's typically within 2-3 kg of DEXA scans (the medical gold standard). For free, in seconds, this gives most of the benefit of a ₹3,000-5,000 body composition scan.
Enter gender, height in cm and weight in kg.
Read LBM by formula and the average.
Compare your LBM to your previous result to track muscle gain or loss.
Each formula uses a regression on weight and height to estimate fat-free mass. Boer (1984) is the most widely used in clinical practice. James (1976) accounts for body shape via weight²/height. Hume (1971) is the oldest of the three.
Boer (M): 0.407·W + 0.267·H − 19.2 Boer (F): 0.252·W + 0.473·H − 48.3 James, Hume use similar regressions with different coefficients
Each formula is a linear regression fit to populations measured by gold-standard methods (densitometry, DEXA, hydrostatic weighing). Boer (1984) is most widely used because it's calibrated to modern, larger populations. James (1976) accounts for body shape effects. Hume (1971) is the oldest but still useful as a comparison. Differences between formulas reflect differences in source populations rather than fundamental disagreements about the math.
LBM includes everything that isn't fat - muscle, bone, organs, blood, water. Muscle itself is roughly 40-50% of total LBM in adults. Bone is 10-15%. Organs and blood about 25%. Water about 60% of total body weight (most of it inside the LBM). This is why LBM doesn't translate directly to muscle mass; it tracks fat-free tissue as a whole. To monitor muscle specifically, combine LBM tracking with strength PRs and progress photos.
Indian populations tend to carry less LBM at the same height compared to Caucasian populations - partly genetic (smaller average bone mass), partly behavioural (less resistance training historically). LBM thresholds for 'healthy' or 'athletic' should be calibrated to your demographic and goal. For most Indian adult males of average height (170 cm), LBM in the 50-55 kg range is typical; serious lifters target 60+ kg.
Boer: 0.407 × 75 + 0.267 × 175 − 19.2 = 57.9 kg. James and Hume produce 56-58 kg range. Average ≈ 57.3 kg LBM. Body fat by inference: (75 − 57.3)/75 = 23.6%. Moderate body fat - typical for sedentary or lightly active males. Target LBM at this height for athletic build: 60-65 kg.
Boer: 0.252 × 60 + 0.473 × 165 − 48.3 = 44.7 kg. Average across formulas ≈ 44 kg LBM. Body fat ~26.7%. Healthy range for adult women. Increasing LBM by 3-5 kg through 12 months of structured resistance training and adequate protein would meaningfully improve metabolic health and aesthetics.
Men typically 50-65 kg LBM at average heights; women 35-50 kg. Trained athletes hit higher. Track your own trend rather than absolute numbers.
They're regression estimates, accurate to within 2-3 kg for most people. DEXA scans give the gold standard but cost money. The formula average is a fine free alternative.
Yes - aggressive deficits or insufficient protein cause muscle loss. Use the Protein Calculator to set adequate intake (1.8-2.0 g/kg) and lift heavy to preserve LBM in a deficit.
No - LBM includes muscle, bone, organs and water. Muscle is roughly 40-50% of LBM. To track muscle specifically, look at strength PRs and progress photos.
BMR is largely driven by LBM - more lean mass means a higher resting metabolism. That's why strength training raises your maintenance calories.
Different formulas give different results. Boer is the modern standard; older calculators may use Hume or older Hume variants.
Body composition, daily energy needs and pregnancy timelines all rest on formulas validated across millions of people, but no single number tells the whole story. The values from this calculator are point estimates with a known margin of error - body fat from skinfold or US Navy method has roughly a ±3% standard error compared to a DEXA scan, and BMR can vary ±10% person to person at the same height and weight. Use these numbers to track trends week over week, not to chase decimal precision day to day.
Pair this tool with the BMR, TDEE, calorie and macro calculators to turn a single measurement into an actionable plan. None of these tools are a substitute for a qualified doctor, registered dietitian or certified strength coach - but they remove the busywork so you spend more time on training and recovery, less on math.
The Lean Body Mass Calculator is part of the Health & Fitness suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.
