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Free FFMI calculator & Fat-Free Mass Index calculator. Calculate your FFMI, muscle mass assessment, and body composition analysis. Our calculator uses the standard FFMI formula to determine muscle mass relative to height with adjusted FFMI for accurate comparisons.
Last updated: February 2, 2026
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Enter your body fat percentage (e.g., 15 for 15%)
Fat-Free Mass Index
20.99
Adjusted FFMI: 20.99 (Excellent)
Fat-Free Mass
68.0 kg
Fat Mass
12.0 kg
Body Fat Percentage
15%
Category: Excellent
Muscle mass is excellent. You have exceptional muscle development.
Muscle Mass Percentile: 75th-90th percentile
Recommendation
Maintain current training intensity and focus on muscle quality and longevity.
FFMI Tips:
Formula
FFMI = FFM / Height²
Measures muscle mass relative to height using fat-free mass
Adjusted Formula
FFMI + 6.1 × (1.8 - H)
Accounts for height bias to provide accurate muscle mass comparison
Components
Fat-Free Mass, Fat Mass
Determines muscle mass and body composition breakdown
Analysis
Complete Body Composition
Provides comprehensive body composition analysis and metrics
Scoring
Percentile & Category
Categorizes muscle mass with percentile rankings and interpretations
Advanced Analysis
Athlete-Specific Metrics
Provides advanced muscle mass assessment for bodybuilders and athletes
For a male, 80 kg, 180 cm tall, 15% body fat:
FFMI
20.2
Category
Above Average
Our FFMI calculator uses the standard Fat-Free Mass Index formula to measure muscle mass relative to height. The calculation applies body composition principles to provide accurate muscle mass assessment and percentile rankings for tracking fitness progress.
FFMI = Fat-Free Mass (kg) / Height (m)²Fat-Free Mass = Weight × (1 - Body Fat %)Adjusted FFMI = FFMI + 6.1 × (1.8 - Height in m)This formula provides accurate muscle mass assessment by measuring fat-free mass relative to height. The adjusted FFMI accounts for height bias, providing fairer comparisons across different body sizes.
Shows how FFMI is calculated from body weight, body fat percentage, and height
FFMI categories help interpret muscle mass relative to population norms. These categories account for gender differences and provide context for understanding your muscle mass development. The adjusted FFMI is particularly useful for comparing individuals of different heights.
Need help with other fitness calculations? Check out our body recomposition calculator and lean body mass calculator.
Get Custom Calculator for Your PlatformResult: FFMI = 21.0, Adjusted FFMI = 21.0, Category: Above Average
This indicates good muscle development. Focus on progressive overload training for continued improvement.
Male: 75 kg, 175 cm, 18% body fat
FFMI: 18.2 (Average, 25th-50th percentile)
Male: 85 kg, 180 cm, 10% body fat
FFMI: 23.1 (Excellent, 75th-90th percentile)
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