Body Fat Percentage,
Beyond the Scale Alone.
Free body composition calculators: Navy body fat method, a BMI-based estimate, lean mass and fat mass split, and waist-to-height ratio.
US Navy Circumference Standard
Accurate within 3% of DEXA scans using only neck, waist, and hip circumference measurements.
Lean Body Mass (LBM)
Know exact pounds of skeletal muscle, bone, and organs to properly size baseline protein intake.
Target Body Fat Timeline
Compute how many pounds of pure adipose tissue must be metabolized to hit 12% or 20% goals.
BodyFatMath Calculators
Navy Body Fat Calculator
The US Navy circumference method — neck, waist (and hips for women) against height — the most validated tape-based estimate.
Lean Mass & Fat Mass Calculator
Split your weight into lean mass and fat mass — the numbers training and cutting decisions actually run on.
Waist-to-Height Ratio Calculator
The risk ratio many clinicians now prefer to BMI: waist under half your height is the line that matters.
BMI-Based Body Fat Estimator
The Deurenberg formula: estimate body fat from BMI, age, and sex — a rough screen when no tape is around.
Evidence-Based Physiology
The tape measure is the best body composition tool you already own
Why circumference methods beat smart scales for trends, and the five-minute protocol that makes them reliable.
Visceral fat: the metabolically loud guest at the table
What makes belly fat different, why it leaves first, and how to measure its departure.
12 mistakes people make with body composition
The recurring errors we see in body composition — what causes each one, and the habit that prevents it.