Body Fat Calculator
Calculate your body fat percentage using multiple methods and track changes over time.
Calculate Body FatLean Body Mass Calculator
Calculate muscle mass with precision, visualize progress with charts, and track your fitness journey
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Lean Body Mass Calculator
Choose your preferred calculation method and get comprehensive analysis with chart visualization
Choose Calculation Method
Body Fat Method
Most accurate if you know your body fat percentage
Recommended for: DEXA, BodPod, or hydrostatic resultsBoer Formula
Research-based estimation without body fat
Recommended for: General population estimatesJames Formula
Alternative scientific estimation
Recommended for: Cross-validationLBM Calculation Methods Comparison
| Method | Accuracy | Requirements | Best For | Limitations |
|---|---|---|---|---|
| Body Fat Method | ⭐⭐⭐⭐⭐ Highest | Accurate body fat % | DEXA, BodPod results | Requires precise BF measurement |
| Boer Formula | ⭐⭐⭐⭐ Very Good | Height, weight, gender | General population | May overestimate in obese |
| James Formula | ⭐⭐⭐ Good | Height, weight, gender | Cross-validation | Less accurate for athletes |
| DEXA Scan | ⭐⭐⭐⭐⭐ Gold Standard | Professional scan | Research, detailed analysis | Expensive, not always available |
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Understanding Lean Body Mass
What is Lean Body Mass?
Lean Body Mass (LBM), also known as Fat-Free Mass (FFM), represents everything in your body except adipose (fat) tissue. Understanding your LBM is crucial for:
Training Optimization
- Setting realistic muscle gain goals
- Tracking true progress beyond weight
- Adjusting training volume and intensity
- Periodization planning
Nutrition Planning
- Calculating accurate protein needs
- Setting appropriate caloric targets
- Monitoring body composition changes
- Cutting vs. bulking decisions
Components of Lean Body Mass
Skeletal Muscle
40-50% of LBM
The muscle you can build through trainingBone Mass
12-15% of LBM
Your skeletal structure and mineral contentOrgans & Tissue
20-25% of LBM
Heart, liver, kidneys, brain, etc.Body Water
60-70% of total weight
Intracellular and extracellular fluidFat-Free Mass Index (FFMI) Complete Guide
FFMI is like BMI but for muscle mass. It shows how much muscle you carry relative to your height, making it an excellent tool for comparing muscle development across different body sizes.
FFMI Formula
FFMI = Lean Body Mass (kg) ÷ (Height in meters)²
Normalized FFMI = FFMI + 6.1 × (1.8 - height in meters)
FFMI Categories and Benchmarks
| FFMI Range | Men | Women | Description | Training Level |
|---|---|---|---|---|
| Below Average | < 18 | < 15 | Low muscle mass, sedentary lifestyle | Untrained |
| Average | 18-20 | 15-17 | Typical for general population | Occasionally active |
| Above Average | 20-22 | 17-19 | Some training experience visible | Regular gym-goer |
| Excellent | 22-25 | 19-21 | Years of dedicated training | Serious athlete/bodybuilder |
| Elite/Suspicious | > 25 | > 21 | Genetic elite or enhanced | Professional/Enhanced |
Natural Limits
Research suggests the natural FFMI limit for drug-free individuals is around 25 for men and 21 for women.
- 95% of natural bodybuilders: FFMI ≤ 25
- Genetic elite may reach 26-27
- Values > 28 strongly suggest PED use
Factors Affecting FFMI
- Genetics: Muscle fiber types, insertions
- Training age: Years of consistent training
- Training quality: Progressive overload
- Nutrition: Adequate protein and calories
- Recovery: Sleep and stress management
Frequently Asked Questions
Which calculation method should I use?
If you have an accurate body fat measurement from DEXA, BodPod, or hydrostatic weighing, use the Body Fat Method for highest accuracy. Otherwise, the Boer Formula is most reliable for general estimates.
What's a realistic FFMI goal for natural lifters?
For men, FFMI 20-22 is achievable with consistent training. FFMI 22-25 represents excellent development requiring years of dedication. For women, aim for FFMI 17-19 initially, with 19-21 being excellent.
How much muscle can I gain naturally?
Most men can gain 40-50 lbs of muscle over their entire training career. Women typically gain about half that amount. Gains are fastest in the first 2-3 years, then slow dramatically.
Can I build muscle and lose fat simultaneously?
Yes, but it's challenging and most effective for beginners, those returning from a break, or individuals with higher body fat. Most experienced lifters see better results focusing on one goal at a time.
Why is my FFMI lower than expected despite training?
Common reasons include: insufficient calories/protein, inadequate training volume, poor recovery, unrealistic expectations, or simply needing more time. Building significant muscle takes years, not months.
How often should I track my lean body mass?
Monthly tracking is sufficient for most people. Body composition changes slowly, and daily fluctuations in weight and hydration can mask real progress. Focus on trends over time.
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