US Navy Body Fat Calculator
Use the official circumference method used by the U.S. Navy to estimate your body fat percentage.
Note: This is an estimate and not a medical diagnosis. For clinical precision, consider DEXA or hydrostatic testing.
What is the US Navy body fat method?
The US Navy body fat calculator estimates body fat percentage from simple tape measurements. It uses neck, waist, and height for men, and neck, waist, hip, and height for women. Because it only needs a flexible measuring tape, it is one of the most practical ways to track body composition over time.
This method became popular because it can be repeated consistently without expensive lab equipment. If you measure under the same conditions each time, trends are often more useful than any single one-time value.
How to measure correctly
For men
- Height: Stand tall without shoes.
- Neck: Measure just below the larynx (Adam's apple), tape level around neck.
- Waist: Measure at navel level, relaxed (do not suck in).
For women
- Height: Stand tall without shoes.
- Neck: Measure below the larynx, tape level.
- Waist: Measure at the narrowest point or natural waist.
- Hips: Measure at the widest point of the glutes/hips.
For best consistency, measure in the morning before food, keep the tape snug but not tight, and repeat each measurement 2–3 times, then average.
US Navy formula (reference)
Male formula
Body Fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Female formula
Body Fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Important: These constants are based on inches, so this calculator automatically converts centimeters to inches when needed.
How to interpret your result
General body fat categories for men
- Essential fat: 2–5%
- Athletes: 6–13%
- Fitness: 14–17%
- Average: 18–24%
- Obesity range: 25%+
General body fat categories for women
- Essential fat: 10–13%
- Athletes: 14–20%
- Fitness: 21–24%
- Average: 25–31%
- Obesity range: 32%+
Use these as broad guidelines. Age, genetics, training history, and health status matter. The best strategy is to compare your own progress month to month.
Why people like a navy body fat calculator
- No expensive equipment needed
- Fast and easy to repeat weekly or monthly
- Better tracking signal than scale weight alone
- Works well in fitness, military prep, and lifestyle coaching
Limitations to understand
Like any estimate, this method has error. Measurement technique, hydration, posture, and tape placement can shift results. It also does not directly measure visceral fat or muscle distribution. If you need highly accurate body composition data for medical reasons, ask a licensed clinician about advanced testing options.
Tips to lower body fat in a sustainable way
- Create a modest calorie deficit (not an extreme one).
- Prioritize protein and whole foods.
- Lift weights 2–4 times per week to preserve lean mass.
- Add daily walking and consistent sleep.
- Track measurements every 2–4 weeks, not every day.
FAQ
Is this better than BMI?
For many people, yes. BMI uses height and weight only, while the US Navy approach uses body measurements that better reflect fat distribution.
How often should I measure?
Every two to four weeks is usually enough. Daily changes are mostly water and digestion, not real fat gain or loss.
What if my numbers fluctuate?
Small swings are normal. Keep measuring under the same conditions and focus on the trend over several months.