US Navy Body Fat Percentage Calculator
Estimate body fat percentage, fat mass, and lean mass using the US Navy circumference (tape measure) method — no scale or scanner required.
Measure neck just below the larynx, waist at the navel, and (for the female formula) hips at the widest point — a cloth or flexible tape measure, held snug but not tight, gives the most accurate reading.
Estimated body fat
16.5%
Fitness
Estimated fat mass
13.2 kg
Estimated lean mass
66.8 kg
Categories shown are the commonly published ACE (American Council on Exercise) body fat classification ranges, for general reference only — not a personalized health assessment.
About this tool
How to use it
- Select your sex, then enter your height and weight.
- Measure and enter your neck circumference (just below the larynx) and waist circumference (at the navel) with a flexible tape measure, held snug but not pulled tight.
- If you selected female, also measure and enter hip circumference at the widest point — the formula for women uses this additional measurement.
- Read your estimated body fat percentage, fat mass, and lean mass together.
Why it matters
Body weight and BMI don't distinguish fat mass from muscle mass — two people at the same height and weight can have very different body compositions. The US Navy circumference method estimates body fat percentage from simple tape-measure readings, without needing a scale, calipers, or a scan, making it one of the most accessible body composition estimates available.
When to use it
Tracking body composition changes over time without access to a DEXA scan, bod pod, or skinfold calipers. Getting a body fat estimate for military, first-responder, or fitness program requirements that specifically reference the Navy method. Getting a second estimate to sanity-check a different method (BIA scale, calipers) that might be giving an inconsistent reading.
Good to know
This uses the Hodgdon & Beckett (1984) circumference formula developed for the US Navy Physical Readiness Program — a real, published equation, not an approximation invented for this tool. Like all circumference-based methods, accuracy depends heavily on correct measurement technique (tape position, tension, and posture) and tends to be less accurate for people with atypical fat distribution or very high or low body fat, compared to direct methods like DEXA scanning. The body fat category labels shown are the commonly published ACE (American Council on Exercise) classification ranges — a general reference point, not a personalized health assessment.
Common questions
How accurate is the tape measure method compared to a DEXA scan or calipers?
Studies generally find the Navy circumference method reasonably accurate for population averages, typically within a few percentage points of more precise methods like DEXA — but it can be less reliable for individuals with atypical fat distribution, very low or very high body fat, or inconsistent measurement technique. It's a practical estimate, not a clinical-grade measurement.
Why does the formula need a hip measurement for women but not men?
The Hodgdon & Beckett equations were derived separately for each sex from population data, and the female formula specifically found hip circumference statistically useful for the estimate where the male formula did not — this reflects how the original research was actually done, not an arbitrary choice.
Where exactly should I measure my waist and neck?
Neck: measure just below the larynx (Adam's apple), with the tape sloping slightly downward at the front. Waist: measure at the navel, standing normally (not sucking in). Hip (women only): measure at the widest point around the buttocks. Keep the tape snug against the skin but not compressing it.
What do the category labels (Essential fat, Athletes, Fitness, Average, Obese) mean?
These are the commonly published ACE (American Council on Exercise) body fat percentage classification ranges, shown here purely as a general reference point for where a percentage typically falls — not a diagnosis or a personalized recommendation for your specific health situation.
Is this a substitute for a medical or professional body composition assessment?
No — this is a widely-used estimation formula for general tracking and reference, not a clinical or diagnostic tool. For a medically precise body composition assessment, a DEXA scan or a qualified professional using calibrated equipment is more reliable.