Body Fat Calculator
Body fat percentage is the proportion of your total body weight that is composed of fat. Unlike BMI, it distinguishes between fat mass and lean mass (muscle, bone, organs, water) — giving a much more accurate picture of body composition.
US Navy Method
This calculator uses the US Navy circumference method, which estimates body fat from simple tape measurements. It is one of the most widely validated field methods, used by the US military for fitness assessments.
Female: BF% = 495 / (1.29579 − 0.35004 × log(waist + hip − neck) + 0.22100 × log(height)) − 450
How to Measure
- Neck: Measure just below the larynx (Adam's apple), with the tape sloping slightly downward at the front.
- Waist (men): Measure at the navel level, fully exhaled.
- Waist (women): Measure at the narrowest point of the abdomen.
- Hip (women only): Measure at the widest point of the hips and buttocks.
Body Fat Categories (ACE)
- Essential Fat — Men: <6%, Women: <14% — Minimum for bodily functions. Dangerous if sustained.
- Athlete — Men: 6–13%, Women: 14–20% — Very lean; typical of competitive athletes.
- Fitness — Men: 14–17%, Women: 21–24% — Above average fitness level.
- Average — Men: 18–24%, Women: 25–31% — Acceptable range for general health.
- Obese — Men: ≥25%, Women: ≥32% — Elevated health risks.
Limitations
The Navy method is an estimate with an error margin of ±3–4%. For precise body composition analysis, use DEXA scans or hydrostatic weighing. This tool is best for tracking trends over time rather than pinning down an exact number.
Frequently Asked Questions
Is lower body fat always better?
No. Going below essential fat levels is dangerous and can cause hormonal disruption, organ failure, and immune suppression. Healthy body fat has a range — not just a floor.
How does this differ from BMI?
BMI uses only height and weight. A muscular person can have a high BMI but low body fat. Body fat percentage directly measures fat composition, making it a far more useful metric for health and fitness goals.