Body Fat Calculator: Estimate Your Body Fat Percentage
A male with a 36" waist, 16" neck, and height of 5'10" has an estimated body fat of approximately 18.6% using the U.S. Navy method. Healthy body fat ranges: men 10-20%, women 18-28%. Essential fat minimums: men 2-5%, women 10-13%.
Estimate Your Body Fat %
U.S. Navy circumference method.
Body Fat Percentage
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Body Fat Categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2-5% | 10-13% |
| Athletes | 6-13% | 14-20% |
| Fitness | 14-17% | 21-24% |
| Average | 18-24% | 25-31% |
| Obese | 25%+ | 32%+ |
How the U.S. Navy Method Works
Men: BF% = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76 Women: BF% = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387
Measurements should be taken:
- Waist: At the narrowest point (men) or at the navel (women)
- Neck: Just below the larynx, sloping slightly downward at front
- Hip (women only): At the widest point of the buttocks
Why Body Fat Matters More Than Weight
Two 180 lb males at 5'10": one at 15% body fat carries 153 lbs of lean mass and 27 lbs of fat. Another at 30% carries 126 lbs of lean mass and 54 lbs of fat. The first looks athletic; the second does not — despite identical scale weight. Track body fat percentage, not just weight, to measure real progress.
1. Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center Report No. 84-29. 1984.
2. Jackson AS, Pollock ML. Generalized equations for predicting body density of men. Br J Nutr. 1978;40(3):497-504. doi:10.1079/BJN19780152
3. American Council on Exercise. Percent Body Fat Norms for Men and Women. ACE Fitness. https://www.acefitness.org/resources/everyone/tools-calculators/percent-body-fat-calculator/
Sources
Frequently Asked Questions
How accurate is the U.S. Navy body fat method?
The U.S. Navy method is accurate to within 3-4% compared to hydrostatic weighing, according to a study by Hodgdon and Beckett (1984). It is most accurate for individuals in the average body fat range (15-30%). It may underestimate very lean individuals and overestimate those with high muscle mass in the waist area.
What is a healthy body fat percentage?
For men: 10-20% is considered healthy, with 14-17% being the fitness range. For women: 18-28% is healthy, with 21-24% being the fitness range. Women naturally carry more essential fat for reproductive function. Athletes may be lower, but going below essential fat levels (2-5% men, 10-13% women) poses serious health risks.
How often should I measure body fat?
Measure every 2-4 weeks under consistent conditions: same time of day, same hydration level, same person taking measurements. Body fat changes slowly — weekly measurements introduce too much noise from measurement variation. Track the trend over months, not individual readings.
Is body fat percentage better than BMI?
For individual assessment, yes. Body fat percentage directly measures adiposity, while BMI is a proxy based on height and weight that cannot distinguish muscle from fat. An athlete with high muscle mass may have a high BMI but low body fat. However, BMI is still useful for population-level health screening.
What is the most accurate way to measure body fat?
DEXA (Dual-Energy X-Ray Absorptiometry) scanning is considered the gold standard, accurate to within 1-2%. Hydrostatic (underwater) weighing and air displacement plethysmography (Bod Pod) are also highly accurate. Bioelectrical impedance scales are convenient but can vary by 5-8%. The Navy method used here is the best free option requiring only a tape measure.