Body Fat Percentage Calculator
Use the U.S. Navy method to calculate your body fat percentage, fat mass, and lean mass from simple circumference measurements.
Waist: measure at navel level; neck: just below the laryngeal prominence.
What Is Body Fat Percentage?
Body fat percentage is the proportion of your total body weight that consists of fat tissue. Body weight and BMI alone don't reflect the muscle-to-fat balance — two people of the same height and weight can have very different body compositions. Body fat percentage fills that gap: it tells you how much of your mass is working tissue (muscle, bone, organs) versus stored fat.
How Does the Navy Method Work?
The U.S. Navy body fat formula was developed for military fitness assessments. It estimates body fat from circumference measurements — no imaging equipment or calipers required, just a tape measure. Its accuracy is approximately ±3–4 percentage points, making it a reliable tool for at-home tracking and trend monitoring.
Female: BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387
For consistent results, take measurements in the morning before eating, with the same tape measure, under the same conditions each time. Waist: at the navel (widest point). Neck: just below the laryngeal prominence (Adam's apple). Hips (women): at the widest point.
Body Fat Percentage Categories
According to American Council on Exercise (ACE) standards:
| Category | Men | Women |
|---|---|---|
| Essential Fat | 2% – 5% | 10% – 13% |
| Athletic | 6% – 13% | 14% – 20% |
| Fitness | 14% – 17% | 21% – 24% |
| Average | 18% – 24% | 25% – 31% |
| Obese | 25%+ | 32%+ |
Essential fat is the minimum required for organ protection, nervous system function, and hormonal balance — falling below this level carries serious health risks. Most recreational athletes operate in the athletic–fitness range. The average range is considered healthy for the general population.
How to Reduce Body Fat
Reducing body fat comes down to two non-negotiable principles: a calorie deficit and muscle-preserving training. Dieting without resistance training causes a significant portion of weight loss to come from muscle — which slows metabolism and leaves body fat percentage relatively unchanged even as the scale drops.
- Calorie deficit: Staying 300–500 kcal below your daily energy expenditure produces sustainable fat loss without excessive muscle breakdown. Larger deficits accelerate muscle loss.
- Protein intake: To preserve muscle in a deficit, research consistently supports 1.6–2.2 g of protein per kg of body weight per day for active individuals (international sports nutrition consensus).
- Resistance training: Strength work protects lean mass during a calorie deficit and supports basal metabolic rate. A program of compound lifts 3 times per week is sufficient.
- Cardiovascular activity: Aerobic work (walking, cycling, HIIT) increases calorie expenditure. Combined with resistance training, it accelerates fat loss without compromising muscle.
- Tracking and consistency: Logging your training, weight, and dietary intake lets you see what's working and make timely adjustments — the difference between plateauing and progressing.
Fat loss is rarely linear. Weekly fluctuations in weight are normal (hydration, glycogen, sleep). The most reliable signal is monthly re-measurement under identical conditions, combined with a consistent training record.
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Download VIGOR FreeThis calculator is for informational purposes only and does not constitute medical advice. If you have a health condition, consult a physician or registered dietitian.