Body Fat Percentage Calculator

Estimate body fat percentage with the US Navy tape, BMI-based or skinfold method, plus category, healthy range and fat and lean mass.

Choose an estimation method
Quick presets
Measurement units
Estimated body fat
Body fat — 0 %
—
Fat mass and lean body mass
0 kgFat mass — weight stored as body fat.
0 kgLean body mass — muscle, bone, organs, water.

Three-method comparison
MethodBody fatNote

Progress log: track measurements over time

    The log keeps measurements only in this page session. Save your dates and numbers elsewhere if you need them later.

    Bridge: from lean mass to energy and protein
    0 kcal/dayResting energy (Katch–McArdle): 370 + 21.6 × lean mass in kg.
    0 g/dayProtein target: about 1.8 g per kg of lean body mass.

    Katch–McArdle uses lean mass, so it adapts to your build better than weight-only formulas. Adjust the protein factor to your own goal and activity.

    For beginners: how to read this result
    Percentage, not weightBody fat percentage is the share of your weight that is fat, so it tells more than weight alone.
    Method changes the numberTape, BMI and skinfold can differ by a few points. Pick one method and stay with it to track change.
    Category, not a targetThe badge shows a general band. A healthy range depends on age, sex and personal goals.
    Lean mass is the engineMore lean mass usually means a higher resting energy need and a higher protein target.
    All three methods are estimates with a typical error of about ±3–4 percentage points. They are less accurate than a DEXA scan or hydrostatic weighing and are not a medical diagnosis. Consult a qualified professional for health decisions.

    How to use it

    Pick an estimation method, then fill the fields it shows. The US Navy method asks for neck and waist circumferences, plus hip for women. The skinfold method asks for three skinfold readings in millimetres. The BMI-based method needs only height, weight, age and sex. Switch units between centimetres/kilograms and inches/pounds at any time, and every field also accepts manual values. The main result shows your body fat percentage and a coloured category badge: essential, athletes, fitness, average or above average.

    The three formulas

    US Navy. For men, body fat is derived from the base-10 logarithm of waist minus neck and the logarithm of height. For women, the waist plus hip minus neck is used instead. The result is scaled by the constant 495 and offset by 450.

    BMI-based (Deurenberg). Body fat = 1.20 x BMI + 0.23 x age – 10.8 x sex – 5.4, where BMI is weight in kilograms divided by height in metres squared, and sex is 1 for men and 0 for women.

    Skinfold (Jackson-Pollock, 3-site). The sum of three skinfolds and age give body density through a sex-specific equation, then body fat = 495 / density – 450. Fat mass is weight times body fat percentage; lean body mass is weight minus fat mass.

    What it also shows

    A healthy body fat range for your age and sex, a fat mass and lean body mass split, a side-by-side comparison of all three methods when enough data is present, a progress log with an inline chart, and a bridge to resting energy use through the Katch-McArdle equation and a protein target based on lean mass.

    What is not included

    This is an estimate, not a clinical measurement. It does not replace DEXA scans, hydrostatic weighing or bioelectrical impedance, does not account for hydration, recent meals, individual fat distribution or athletic body types beyond the formula assumptions, and is not a medical diagnosis. Typical error is about 3 to 4 percentage points. Consult a qualified professional for health decisions.