Estimate your body fat percentage with the US Navy circumference method — just a tape measure, no calipers or scans. Separate formulas for men and women, with a visual category indicator.
Estimated body fat
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US Navy method (circumference formula). Measure waist at the navel, relaxed — not sucked in. Neck just below the Adam's apple. Women measure hips at the widest point. Typical accuracy is within 3–4% of a DEXA scan. General information, not medical advice.
2026 guidelines: healthy body fat is roughly 10–20% for men and 18–28% for women, varying by age. Athletes run lower (6–13% men, 14–20% women). The Navy method used here estimates within ±3% of DEXA scans for most people.
Is the Navy body fat method accurate in 2026?
Yes — the US Navy circumference method remains a validated, widely used estimate in 2026, accurate within about 3 percentage points for most adults. For clinical precision, DEXA or hydrostatic weighing are the gold standards.
What is the Navy body fat method?
Forget expensive scans and awkward caliper pinches. Decades ago, the US Navy came up with a clever shortcut: a simple tape measure around your waist and neck (women add hips), plus your height, is enough to estimate your body fat percentage. It was designed as a quick field test for sailors — no lab, no gadgets, no appointment. And it holds up surprisingly well: for most people it lands within about 3–4% of a DEXA scan, which is plenty close enough to tell whether your training and diet are actually working.
Stand relaxed and breathe normally. Wrap the tape snugly but not tight — it should lie flat on the skin without pressing in. Take each measurement twice and use the average. Measure at the same time of day each time you check, and focus on the trend over weeks rather than a single number.
Frequently asked questions
What is the Navy body fat method?
It is a tape-measure formula the US Navy developed to check sailors' fitness without lab equipment. Measure your waist and neck (women add hips), plug in your height, and the formula estimates your body fat percentage — a two-minute check you can do at home, no calipers or scans needed.
How accurate is the Navy body fat calculator?
It is typically within 3–4% of DEXA scan results for most people. Measure carefully — a relaxed tape at the right spots — and use the same method each time to track your trend.
What is a healthy body fat percentage?
For men, fitness is roughly 14–17% and obesity starts around 25%. For women, fitness is roughly 21–24% and obesity starts around 32%. Athletes are lower, and essential fat is about 2–5% for men and 10–13% for women.
Is this body fat calculator free?
Yes. It is 100% free with no signup required.
Should I measure in inches or centimeters?
The Navy formula was derived in inches, but this calculator converts automatically — just use whichever unit you actually measured in. What matters far more is measuring the same way every time, so your readings stay comparable and the trend is trustworthy.
Why is my Navy result different from my smart scale?
Smart scales use bioelectrical impedance, which swings with hydration, meals, and even sweaty feet; the Navy tape method is steadier from day to day. Pick one method, use it consistently, and judge progress by the trend over several weeks rather than any single number.
How often should I re-measure body fat?
Every 2–4 weeks is plenty — body fat changes slowly, and daily noise hides real progress. Measure at the same time of day, relaxed, before eating, and log it; a downward slope over two months beats any single 'good' reading.
How the Navy body fat formula works
The US Navy needed a fast field fitness test that didn't require lab equipment, so researchers regressed simple tape measurements against underwater weighing — the gold standard — and produced equations that estimate body-fat percentage from circumferences plus height. The result is a two-minute check you can do at home with a tape measure, no calipers or scans.
The formulas (all measurements in inches; log is base-10): Men: % = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76 Women: % = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387 The waist-minus-neck term captures trunk fat while subtracting neck musculature; height normalizes for frame size.
Worked example — a man with a 34″ waist, 15″ neck, 70″ tall: waist − neck = 19; log10(19) = 1.2788 → 86.010 × 1.2788 = 110.00; log10(70) = 1.8451 → 70.041 × 1.8451 = 129.24. Body fat = 110.00 − 129.24 + 36.76 = 17.5% — squarely in the fit range for men (14–17% fitness, 18–24% average).
Practical tips: measure relaxed (don't suck in), keep the tape horizontal, and measure in the morning before eating — then track the trend over weeks, not any single reading. Limitation: expect ±3–4% versus a DEXA scan, and the formula skews for very muscular builds, where a thick neck and waist read as "fat" that is actually muscle.
Measuring landmarks that make or break accuracy: small tape-placement errors swing the result by whole percentage points, because the formula is logarithmic — precision matters more than with linear formulas. Men: measure the waist at the navel (not the narrowest point), relaxed at end of a normal exhale; the neck just below the Adam's apple, tape perpendicular to the spine. Women: waist at the narrowest point (natural waistline), hips at the widest point around the buttocks, neck the same as men. Keep the tape snug but not compressing skin — "two-finger" tightness is the rule of thumb. For context on accuracy: DEXA scans (±1–2%) remain the reference, hydrostatic weighing ±2–3%, the Navy method ±3–4%, bioimpedance scales ±5–8% depending on hydration, and visual estimates ±5%+. The Navy method's real strength isn't precision — it's repeatability for tracking change.