Two methods, different inputs
Navy Method uses circumference measurements — neck, waist, and hip (women only). More accurate than the BMI method because it accounts for body shape, not just height and weight. Measure with a flexible tape, not a rigid one.
BMI Method estimates body fat from your BMI and age. Less accurate but useful if you don’t have a tape measure. Feed your BMI from the BMI calculator.
How to measure correctly
Neck: measure just below the larynx (Adam’s apple), slightly downward slope at the front.
Waist: measure at the navel, not the narrowest point. Stand relaxed, don’t suck in.
Hip (women): measure at the widest point of the hips and buttocks.
Take measurements in the morning before eating. Average two readings if they differ.
Body fat categories
For men: essential fat is 2–5%, athletic is 6–13%, fitness is 14–17%, average is 18–24%, obese is 25%+.
For women: essential fat is 10–13%, athletic is 14–20%, fitness is 21–24%, average is 25–31%, obese is 32%+.
Indians tend to carry more visceral fat at lower body fat percentages than Western populations. The “average” category carries more health risk than the number suggests.
Fat mass vs lean mass
The calculator shows how much of your weight is fat and how much is lean mass (muscle, bone, organs, water). Lean mass is what you want to protect during weight loss. A 500 kcal deficit from the TDEE calculator with adequate protein preserves it.
Related: BMI Calculator · TDEE Calculator · Water Intake Calculator