Use this US Navy body fat calculator to estimate body fat percentage from circumference measurements. It works for men and women and supports both imperial and metric units.
What is a Navy fat calculator?
A Navy fat calculator estimates your body fat percentage using body measurements instead of scale weight alone. The method is based on the U.S. Navy circumference formula, which has been used for fitness screening in military settings. It can be more informative than BMI because it focuses on fat distribution and body composition rather than total weight.
How the Navy body fat formula works
The calculator uses logarithmic equations and measurements that are easy to take at home. Measurements should be in the same unit (all inches or all centimeters), and this page automatically converts metric inputs before calculation.
Men
Body Fat % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Women
Body Fat % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
How to take accurate measurements
- Height: Stand straight without shoes.
- Neck: Measure just below the larynx (Adam’s apple) with tape level around the neck.
- Waist: Measure at the narrowest point for women, and around the navel area for men.
- Hip (women): Measure at the widest part of the hips/glutes.
- Keep the tape snug but not compressing skin.
- Take each measurement 2–3 times and use the average.
How to interpret your body fat result
Body fat percentage categories vary slightly by organization, but this calculator uses practical fitness ranges:
- Men: Essential (2–5%), Athlete (6–13%), Fitness (14–17%), Average (18–24%), Obese (25%+)
- Women: Essential (10–13%), Athlete (14–20%), Fitness (21–24%), Average (25–31%), Obese (32%+)
These are not diagnoses, but they can be useful for tracking trends and setting goals around health, performance, and recomposition.
Reference Navy screening limits by age
If you enter age, the calculator also compares your estimate to common Navy-style screening cutoffs:
| Age | Male max body fat | Female max body fat |
|---|---|---|
| 17–21 | 22% | 33% |
| 22–29 | 23% | 34% |
| 30–39 | 24% | 35% |
| 40+ | 26% | 36% |
Why this is often better than BMI alone
BMI can misclassify muscular people as overweight and underestimate risk in people with low muscle mass. A body fat percentage calculator gives a clearer estimate of your current composition and can better reflect fat-loss progress. If your weight is stable but your waist measurement drops, that usually indicates a healthier body composition trend.
Tips to improve body composition
1) Prioritize protein intake
Aim for high-quality protein spread across meals to support muscle retention while reducing fat.
2) Lift weights consistently
Resistance training helps preserve or gain lean tissue, which improves long-term metabolic health.
3) Use a moderate calorie deficit
Avoid crash dieting. A sustainable deficit is usually better for energy, compliance, and muscle maintenance.
4) Track measurements, not only scale weight
Use your waist, neck, and hip trends along with progress photos and strength performance for a fuller picture.
FAQ
Is this calculator exact?
No field method is perfect. This is an estimate, but it is practical and consistent when measurements are done carefully.
How often should I check body fat?
Every 2–4 weeks is enough for most people. Daily changes are mostly hydration and measurement noise.
Should I rely on one metric only?
No. Use body fat percentage, strength progress, energy levels, and medical markers together for better decisions.