Body Fat Calculator
Estimate your body fat percentage with the US Navy tape method from neck, waist and hip measurements — with ACE category, fat and lean mass.
About the Body Fat Calculator
This body fat calculator uses the US Navy circumference method — a validated tape-measure technique the military uses for body-composition screening. Enter your height, neck and waist measurements (women also add hip), in metric or imperial units, and it estimates your body fat percentage instantly. Add your weight to also see your fat mass and lean body mass in kilograms or pounds.
The formulas are logarithmic: for men, body fat is derived from waist minus neck relative to height; for women, from waist plus hip minus neck. Your result is classified against the widely used ACE (American Council on Exercise) chart: essential fat, athletes, fitness, average and obese, with different ranges for men (2–5% essential) and women (10–13% essential) because women naturally carry more fat.
Circumference methods typically land within about 3–4% of laboratory techniques like DEXA when measurements are taken carefully — measure at the right landmarks, keep the tape level and snug but not compressing the skin, and take readings at the same time of day. It is a far more informative metric than BMI alone, since it distinguishes fat from muscle.
How to Use the Body Fat Calculator
- 1Select your gender and preferred units (cm/kg or in/lbs).
- 2Enter your height, neck circumference (below the larynx) and waist circumference.
- 3For women, also enter the hip circumference at the widest point.
- 4Optionally enter your weight to see fat mass and lean mass.
- 5Read your body fat percentage and ACE category instantly.
Frequently Asked Questions
How accurate is the US Navy body fat method?
Studies show the Navy circumference method typically estimates body fat within about 3–4 percentage points of DEXA scans for most people, which is comparable to consumer bioimpedance scales. Accuracy depends heavily on measurement technique — a tape pulled too tight or placed at the wrong landmark easily shifts the result by 1–2%. It is best used to track change over time.
What is a healthy body fat percentage?
Per the ACE chart, a 'fitness' level is 14–17% for men and 21–24% for women, while 'average' extends to 24% and 31% respectively. Essential fat — the minimum needed for basic physiology — is 2–5% for men and 10–13% for women. Health risk rises meaningfully above 25% (men) and 32% (women), which the chart classes as obese.
Where exactly should I place the measuring tape?
Neck: just below the larynx (Adam's apple), sloping slightly downward at the front. Waist: for men, horizontally at navel level; for women, at the narrowest point of the torso. Hips (women): around the widest part of the buttocks. Keep the tape parallel to the floor, snug against the skin without compressing it, and measure after a normal exhale.
Why do women need a hip measurement and men don't?
Men and women store fat differently. Women typically carry proportionally more fat around the hips and thighs, so the Navy formula for women adds the hip circumference to capture that distribution. The men's formula relies on waist minus neck alone, since abdominal storage dominates male fat patterns. Using the wrong gender formula produces significantly skewed results.
Is body fat percentage better than BMI?
For assessing body composition, yes. BMI only relates weight to height, so a muscular athlete and a sedentary person can share the same BMI with very different health profiles. Body fat percentage separates fat from lean tissue directly. The two work well together: BMI for quick population-level screening, body fat for a more individual picture.