Free Body Fat Calculator — Navy Method
Estimate your body fat percentage using the US Navy circumference method. Enter your measurements to get fat mass, lean mass, and your fitness category. Free, no signup required.
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Neck: Measure just below the larynx (Adam's apple), perpendicular to the long axis of the neck. Keep the tape snug but not compressing the skin.
Waist (men): Measure horizontally at the level of the navel. Exhale normally and measure at the end of the exhale — do not suck in.
Waist (women): Measure at the narrowest point of the abdomen, typically just above the navel.
Hip (women only): Measure at the widest point around the hips and buttocks, keeping the tape horizontal.
Best time to measure: First thing in the morning before eating or drinking. Repeat 2–3 times and use the average for each measurement.
Body Fat Category Reference
| 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%+ |
Ranges based on American Council on Exercise (ACE) classification guidelines.
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Frequently Asked Questions
How accurate is the Navy body fat method?
The US Navy circumference method is accurate to within 3-4% body fat for most people compared to DEXA scan. It is more practical than skinfold calipers because it only requires a soft measuring tape and is not dependent on the skill of the measurer. For best results, measure circumferences first thing in the morning before eating.
Where do I measure waist circumference for body fat?
For males, measure the waist at the level of the navel (belly button). For females, measure at the narrowest point of the abdomen, typically just above the navel. Do not suck in or hold your breath — measure at the end of a normal exhale. The Navy formula is sensitive to waist measurement, so consistency matters.
What body fat percentage is considered athletic?
For men, athletic body fat is typically 6–13%. For women, athletic body fat is 14–20%. Competitive bodybuilders on stage are typically 4–6% (men) or 10–12% (women), which is below sustainable athletic levels. A "fitness" range — 14–17% for men and 21–24% for women — is realistic for most active people year-round.
How is body fat different from BMI?
BMI (Body Mass Index) uses only height and weight, so it cannot distinguish between muscle and fat. A lean, muscular person may be classified as overweight by BMI. Body fat percentage measures the actual proportion of fat to total mass, making it a far more useful metric for athletes and anyone focused on body composition rather than just scale weight.