Body Fat
Calculator

What is body fat percentage?

Body fat percentage is the share of your total body weight that is fat, as opposed to lean mass (muscle, bone, organs and water). It's a more meaningful composition measure than weight or BMI alone, because two people at the same weight can look and function very differently depending on how much of that weight is muscle versus fat. Tracking body fat tells you whether you're losing fat or muscle when you diet — something the scale can't reveal on its own.

How the US Navy method works

This calculator uses the US Navy (Hodgdon-Beckett) method, a circumference-based equation the military uses for fitness assessments. It estimates body fat from your height, neck and waist (and hips for women) using a logarithmic formula validated against more advanced scans. Its appeal is practicality: all you need is a tape measure, and it's free. While not as precise as a DEXA scan or hydrostatic weighing, it's well-regarded for an at-home estimate and excellent for tracking change over time.

How to take the measurements

Accuracy depends on good measurements. Measure your neck just below the larynx (Adam's apple), sloping slightly downward at the front. Measure your waist at navel level for men, and at the narrowest point for women. For women, also measure hips at the widest point of the buttocks. Keep the tape level and snug — firm against the skin but not digging in — and don't suck in or hold your breath. Taking each measurement two or three times and averaging improves consistency.

Body fat categories

Reference ranges from the American Council on Exercise, which differ by sex:

Category	Men	Women
Essential fat	2–5%	10–13%
Athletes	6–13%	14–20%
Fitness	14–17%	21–24%
Average	18–24%	25–31%
Obese	25%+	32%+

Women carry more essential fat than men — it's biologically necessary — which is why the healthy ranges sit higher. "Essential fat" is the minimum needed for basic physiological function; going below it is unhealthy.

Why body fat beats BMI for composition

BMI can't tell muscle from fat, so it misclassifies muscular people as overweight and can miss "skinny fat" individuals who are light but carry little muscle. Body fat percentage looks past total weight to what you're actually made of. That makes it far more useful for athletes, for anyone strength training, and for judging whether a weight-loss effort is trimming fat or eroding muscle. For the fullest picture, use both — check your BMI and your body fat together.

How accurate is it?

The tape method is an estimate, typically within a few percentage points of a DEXA scan for most people, but it can drift if measurements are sloppy or your fat distribution is unusual. Its real strength is tracking change: measure under the same conditions — same time of day, same tape, same technique — and the trend over weeks will be reliable even if the absolute number isn't perfect. Don't chase the decimal; watch the direction.

Other ways to measure body fat

The tape method is the most accessible, but it's worth knowing the alternatives. Skinfold calipers pinch the fat under the skin at several sites — cheap and reasonably accurate in trained hands, but technique-dependent. Bioelectrical impedance (the body-fat scales and handheld devices) sends a tiny current through the body; convenient but easily skewed by hydration. DEXA scans and hydrostatic weighing are the gold standards used in research, accurate but costly and not something you'd do regularly. For most people, the Navy tape method hits the sweet spot of free, repeatable and good enough to track progress.

How to lower your body fat

Reducing body fat comes down to a sustained, moderate calorie deficit combined with enough protein and resistance training to hold onto muscle. The deficit drives fat loss (plan it with the TDEE calculator); the protein and lifting ensure the weight you lose is fat rather than muscle, which keeps your percentage dropping in the right way. Cardio — walking or running — adds to the deficit and brings its own health benefits. There's no way to "spot reduce" fat from one area; the body draws it down overall, in an order largely set by genetics.

Body fat and health

Both too much and too little body fat carry risks. Excess fat, especially around the abdomen, is linked to metabolic and cardiovascular problems. But fat is also essential — it cushions organs, stores energy and supports hormone production — so dropping below the essential threshold (around 2–5% for men, 10–13% for women) is dangerous, not impressive. The healthiest place to be is within the "fitness" or "average" bands for your sex, where you have plenty of energy and function without carrying excess.

The spot-reduction myth

A persistent fitness myth is that you can burn fat from a specific area by training it — endless crunches for belly fat, say. The evidence is clear that this doesn't work: when you're in a calorie deficit, your body draws fat from stores all over, in an order largely dictated by genetics and hormones, not by which muscle you exercise. Targeted exercises build the muscle underneath, which is worthwhile, but they won't preferentially strip the fat on top. The route to a lower reading anywhere is an overall reduction in body fat — through diet, activity and patience — not localized "toning."

Using your result

Treat your body fat percentage as one informative data point, not a scorecard. If your goal is fat loss, combine it with a sensible calorie deficit (see our TDEE calculator) and resistance training to keep muscle. Re-measure every few weeks rather than daily, since body fat changes slowly. And remember that health is about more than a single percentage — strength, fitness, energy and habits all matter alongside it.