Body Fat Calculator
Estimate body fat percentage from neck, waist and (for women) hip measurements using the U.S. Navy method.
Athletic
Healthy body-fat ranges differ by sex — your 11.5% estimate is placed against typical categories for men.
Estimate only — accuracy depends on careful, consistent tape measurements. DEXA scans are more precise.
About the Body Fat Calculator
This calculator estimates body fat percentage from tape-measure circumferences instead of a scan, using a formula the U.S. Navy developed to screen recruits quickly and cheaply. It trades precision for convenience — a DEXA scan or hydrostatic weighing will give a more exact number, but neither is something most people can do at home with a tape measure and two minutes.
Its real value shows up over time rather than as a single reading: because it's cheap to repeat, tracking the same measurements weekly or monthly tends to reveal a trend even if the absolute percentage is off by a point or two. Athletes, dieters tracking a cut, and anyone curious how their composition is shifting alongside the number on the scale are the typical users.
As with any home body-composition estimate, treat this as general fitness information rather than a clinical measurement — measuring technique affects accuracy more than most people expect, and it's not a substitute for a medical assessment. Your measurements are calculated locally and never leave your device.
How it’s calculated
The U.S. Navy method estimates body fat from circumference measurements — neck and waist for men, with hip added for women — run through a formula built on log-scaled ratios. Women include a hip measurement because fat tends to distribute differently by sex, typically more around the hips and thighs for women versus more centrally for men, and the extra measurement point improves the estimate's accuracy for that pattern.
Because the formula is sensitive to exactly where and how snugly you measure, small technique differences — measuring the waist an inch higher or lower, or pulling the tape too tight — can shift the result more than an actual change in body fat would. Measuring at the same spot, at the same time of day, each time you check matters more than any single reading.
Frequently asked questions
How accurate is the Navy body fat method?
It's generally within a few percentage points of more precise methods like DEXA for most people, which makes it good for tracking change over time, but it can be noticeably less accurate for people at very low or very high body fat levels.
What is a healthy body fat percentage?
Healthy ranges differ by sex — roughly 14–24% is often considered fit-to-acceptable for women and 6–17% for men, though exact "healthy" cutoffs vary by source and by age. The gauge above places your estimate against typical category bands for your sex.
Why does the calculator ask for a hip measurement only for women?
The formula was built separately for each sex based on where body fat typically accumulates — since women's fat distribution more often includes the hip area, adding that measurement improves the estimate's accuracy for women specifically.
Is a tape-measure method as good as calipers or a DEXA scan?
No single home method matches a DEXA scan for precision, but calipers and the Navy tape method are both reasonable, low-cost ways to estimate body fat and — more usefully — to track whether it's trending up or down over time.
How do I measure my waist and neck correctly?
Measure your neck just below the larynx, and your waist at the narrowest point (men) or at the navel (women), keeping the tape snug but not compressing the skin. Measuring at the same time of day, ideally in the morning, keeps repeat readings comparable.
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