Measure your body weight
Measure your body fat percentage
Calculate lean body mass using: body weight × (1 – body fat percentage)
Use skinfold calipers to estimate body fat percentage
Use bioelectrical impedance scales to estimate body fat percentage
Use DEXA scans for a more accurate body composition measurement
Use hydrostatic weighing to estimate body fat percentage
Use air displacement plethysmography to estimate body fat percentage
Subtract fat mass from total body weight to get lean body mass
Recheck measurements regularly to track changes over time