Calculate your body fat percentage using the widely-used US Navy circumference method — no special equipment needed.
Reasonably accurate for most people (within a few percentage points) and widely used since it requires no special equipment, though less precise than DEXA scans or hydrostatic weighing.
Height, neck circumference, and waist circumference for men. Women additionally need hip circumference.
Typically at the navel level, measured while standing relaxed, not pulled in tight.
This tool estimates body fat percentage using the US Navy circumference method, a formula developed by the US Navy as a practical, equipment-free way to estimate body fat using just a measuring tape and a few body circumference measurements.
Unlike BMI, which only considers height and weight, the Navy method uses circumference measurements — neck, waist, and (for women) hips — combined with height, in a logarithmic formula that correlates reasonably well with more precise body fat measurement techniques. This makes it more representative of actual body composition than weight-based measures alone, since it accounts for where body mass is distributed rather than just total weight.
General ranges (these vary somewhat by source and age): for men, roughly 6-13% is considered athletic, 14-17% fitness, 18-24% average, and 25%+ is generally categorized as obese. For women, ranges run higher due to essential fat differences: roughly 14-20% athletic, 21-24% fitness, 25-31% average, and 32%+ generally categorized as obese.
All calculations run directly in your browser — your measurements are never sent to a server.
For the most reliable estimate, measure your neck just below the larynx (Adam's apple), keeping the tape level, and measure your waist at the navel while standing relaxed rather than sucking in your stomach. Women should also measure hip circumference at the widest point of the hips. Taking each measurement two or three times and using the average helps reduce small errors from tape placement or tension.
The US Navy formula accounts for the fact that body fat is typically distributed differently between men and women, and that women naturally carry a higher percentage of essential fat. This is why the calculation for women factors in hip circumference alongside neck and waist, while the male formula relies on neck and waist alone — using the gender-matched formula is what keeps the estimate meaningful rather than simply plugging numbers into a generic equation.
Because the method needs nothing beyond a tape measure, it's commonly used by personal trainers and gym-goers to track body composition changes over weeks or months without access to a DEXA scan or bod pod. Re-measuring every few weeks with consistent technique (same time of day, same tape tension) gives a more useful trend than a single one-off reading, since body fat percentage naturally fluctuates slightly day to day with hydration and other factors.
The US Navy method is an estimate based on statistical correlation between circumference measurements and body fat, not a direct measurement like a DEXA scan or hydrostatic weighing. It can be less accurate for people with atypical body shapes, very high muscle mass, or body fat distributions that differ from the population the formula was originally calibrated on. Treat the result as a useful tracking tool rather than a clinically precise figure.
Athletic ranges (roughly 6-13% for men, 14-20% for women) represent visible muscle definition and are typically maintained only with disciplined training and diet, not a casual baseline target. Most people pursuing general fitness are better served aiming for the fitness or average ranges first, since extremely low body fat percentages can be difficult to sustain and, in some cases, are associated with health trade-offs rather than benefits.
People searching for this tool often use phrases like "navy body fat calculator," "body fat percentage from measurements," "how to calculate body fat without calipers," "body fat calculator men and women," and "waist neck height body fat formula." This calculator's gender-specific Navy method covers all of these directly.
Weight on its own doesn't reveal whether a change came from muscle gain, fat loss, or water fluctuation, which is why pairing this body fat estimate with a regular weigh-in gives a clearer picture of real progress. Someone who loses fat while gaining muscle may see their scale weight stay flat even as their body fat percentage drops, something a weight-only tracking approach would misread as no progress at all.
If you need a highly accurate body fat reading — for a medical reason, a bodybuilding competition, or detailed research — a DEXA scan, hydrostatic (underwater) weighing, or air displacement plethysmography (Bod Pod) will give a more precise figure than any circumference-based formula. For routine self-tracking and general fitness goals, though, the US Navy method offers a practical and consistent way to monitor trends without specialized equipment or cost.