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Body Fat Calculator – US Navy Method & Body Composition Analysis

Body Fat Calculator

Measure just below Adam's apple

Measure at navel (men) or smallest point (women)

Measure at widest point over buttocks

For lean mass / fat mass calculation

The Body Fat Calculator estimates your body fat percentage using the US Navy Method, which is based on circumference measurements (neck, waist, and hip for women). It also calculates lean body mass and fat mass if you provide your weight. This body composition tool is more accurate than BMI alone and is widely used by fitness professionals, athletes, and individuals tracking their health goals. Whether you are on a weight loss journey, building muscle, or simply curious, this body fat percentage calculator gives you a personalised estimate.

Body Fat Percentage RangesMen: 6‑14% Athletes | 15‑17% Fitness | 18‑24% AcceptableWomen: 14‑20% Athletes | 21‑24% Fitness | 25‑31% AcceptableUS Navy Method uses circumference measurementsNeck, waist, and hip (for women)More accurate than BMI alone

How the US Navy Method Works

For men: % Body Fat = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76

For women: % Body Fat = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387

All measurements in inches.

How to Use This Body Fat Calculator

  1. Select metric (cm) or imperial (in).
  2. Choose your gender.
  3. Enter your height, neck, waist, and hip (women only) measurements.
  4. (Optional) Enter your weight to see lean mass and fat mass.
  5. Click “Calculate” to see your body fat percentage and category.

Why Body Fat Percentage Matters

  • Health risk assessment: High body fat is linked to diabetes, heart disease, and metabolic syndrome.
  • Fitness tracking: Changes in body fat are a better indicator of progress than weight alone.
  • Body composition goals: Helps distinguish between fat loss and muscle gain.

Understanding Body Fat Percentage – More Than Just a Number

Your body fat percentage is the proportion of fat mass to total body weight. Unlike BMI, which only considers height and weight, body fat percentage gives a clearer picture of your body composition. Essential fat (necessary for bodily functions) is about 5% for men and 13% for women. Athletes often have lower body fat, but going too low can harm hormone production and immunity. This body fat calculator helps you identify a healthy range based on your gender and measurements.

How to measure accurately: Use a flexible tape measure, keep the tape snug but not compressing skin, and measure at the same time of day (morning is best). For neck, measure just below the Adam's apple. For waist, measure at the navel (men) or the narrowest point (women). For hips (women), measure at the widest part of the buttocks. Consistency is key for tracking changes over time.

Limitations of the US Navy method: It assumes a typical fat distribution pattern. People with very large muscles or unusual body shapes may get less accurate results. It is still far better than BMI for most individuals. For clinical precision, methods like DEXA, hydrostatic weighing, or air displacement plethysmography (Bod Pod) are used. However, this body fat calculator is an excellent free tool for home use.

Using this calculator for weight loss: If your body fat is above the recommended range, aim to lose 0.5‑1% of body fat per month through a combination of resistance training, cardio, and a modest calorie deficit. Recalculate every 2‑4 weeks to track progress. If your body fat is already in the athlete range, focus on performance goals. Bookmark this body fat percentage calculator to use as a long‑term fitness tracker.

Step‑by‑Step Manual Example

Woman, 165 cm, neck 32 cm, waist 70 cm, hip 90 cm:

Convert to inches: 165/2.54=65.0", 32/2.54=12.6", 70/2.54=27.6", 90/2.54=35.4"

Formula: 163.205×log10(27.6+35.4−12.6) − 97.684×log10(65) − 78.387

= 163.205×log10(50.4) − 97.684×1.8129 − 78.387 = 163.205×1.702 − 177.1 − 78.387 ≈ 277.7 − 255.5 = 22.2% body fat

Frequently Asked Questions about Body Fat

How accurate is the US Navy body fat method?
The US Navy method is considered one of the most accurate circumference‑based methods, with typical error of ±3‑4% compared to DEXA scans. It is widely used by military and fitness professionals.
Do I need to measure hips for men?
No, the US Navy method does not require hip measurement for men. Only women need hip circumference.
How should I take measurements?
Use a flexible tape measure. For neck, measure just below the Adam's apple. For waist, measure at the navel level (men) or smallest point (women). For hips (women), measure at the widest point over the buttocks.
What is a healthy body fat percentage?
For men, 15‑20% is good; for women, 20‑30% is healthy. Athletes often have lower percentages. Essential fat is ~5% for men and ~13% for women.