Navy Body Fat Calculator

A healthy body fat percentage is roughly 14–17% for men and 21–24% for women under ACE guidelines — this calculator estimates yours from U.S. Navy tape measurements.

About the US Navy body fat calculator method

This US Navy body fat calculator estimates body fat percentage from body circumferences rather than skinfolds or scans. Men provide neck and waist measurements; women add a hip measurement, because fat distribution differs. Those numbers, combined with your height, go into a logarithmic formula developed for the U.S. Navy that has held up reasonably well against more precise methods.

Its big advantage is convenience: a tape measure costs little and you can repeat the process at home any time. That makes it well suited to tracking change over weeks and months. The trade-off is precision — DEXA scans and hydrostatic weighing are more accurate, and the tape method can be thrown off by measuring technique, posture, and how much you've had to drink.

Getting a reliable reading

• Use a flexible tape and keep it level and snug, without digging into the skin.
• Measure the neck just below the larynx, the waist at the navel, and hips at the widest point.
• Stand relaxed and breathe normally — don't suck in.
• Measure at the same time of day, ideally in the morning, for comparable results over time.

Because it's an estimate, the trend matters more than any single number. If the percentage drifts down over a month while your training and diet are consistent, that's a good sign — regardless of the exact decimal. Pair this with our BMI calculator for a fuller picture of body composition.

Body-fat categories

Category ranges follow American Council on Exercise (ACE) guidelines and match the calculator's output.

The error bar is wider than the category

Set the table above next to the accuracy of the method that fills it in, and an uncomfortable thing becomes obvious. The US Navy tape method carries a standard error of roughly 3.6 to 3.8 percentage points against a DXA scan. Call it ±3.7. That means a single reading spans about 7.4 points end to end.

The Fitness band for men is four points wide, 14% to 17%. So the uncertainty on your measurement is nearly twice the width of the entire category it puts you in. Even the Average band, at seven points, is narrower than the error.

Band widths are the ACE ranges this calculator uses. The error figure is the standard error of the Navy circumference method against DXA, as set out in our guide to measuring body fat.

Worked through: a man who measures 16% here is, on the method's own error, somewhere between 12.3% and 19.7%. That single reading is consistent with him being Athletic, Fitness, or Average — three of the five bands on this page. The calculator will confidently print one word. The measurement does not support one word.

This is not an argument against measuring. It is an argument about what to do with the number. Much of that error stays put between readings. This method's one real strength, as our measuring guide puts it, is repeatability: taking a circumference has almost no operator-to-operator variation, so the same tape on the same landmarks tends to be wrong in the same direction each time. The absolute figure is soft; the change between two readings taken the same way is a good deal firmer than either reading on its own. Someone who goes 20% → 17% over three months has very likely lost fat, even though neither number is reliable to the point.

So: ignore the category, especially near a boundary, and track the direction. Measure at the same time of day, with the same tape, on the same landmarks, and compare with yourself rather than with a table. If you need the absolute number to be right — for a competition weight or a clinical reason — a DXA scan is within 1 to 2 points and this method is not a substitute for it.

Formula: U.S. Navy circumference method, Hodgdon & Beckett, Naval Health Research Center Report 84-11 (1984). Body-fat category ranges follow American Council on Exercise (ACE) guidelines. The formula is named for its origin, not its current use: since 1 January 2026 the Navy screens body composition on waist-to-height ratio rather than body fat percentage. Educational estimate, not medical advice.