Body Fat Calculator
Estimate your body fat percentage with nothing but a tape measure, using the US Navy method. Enter a few body measurements and your height, and the calculator returns your estimated body fat percentage, the fitness category it falls into, and — if you add your weight — your fat mass and lean body mass.
Estimated body fat
17%
Average
How to Use
Pick metric or imperial units and your sex, then measure your neck, waist, and (for women) hips with a tape measure, along with your height. Enter the numbers and your body fat percentage appears instantly, with your category. Add your weight to also see your fat mass and lean mass. Measure on bare skin, keep the tape level and snug but not compressing, and measure the waist at the navel.
Why This Tool Is Useful
Body fat percentage tells you far more about your health and fitness than weight or BMI alone, because it separates fat from muscle. The US Navy method needs only a tape measure — no calipers, scales, or scans — so you can track changes at home over time. It is a solid estimate for trend-tracking, though not as precise as a DEXA scan. Note: results are general estimates for informational purposes, not medical advice — consult a professional for a clinical assessment.
How the US Navy Body Fat Method Works
The US Navy formula estimates body fat from the circumference of your neck and waist (plus hips for women) relative to your height. The idea is that fat distribution at these sites correlates with overall body fat, so a few tape measurements can approximate it without specialist equipment.
For men it uses neck and waist; for women it adds the hip measurement, because fat distribution differs. The calculator handles the math for both metric and imperial inputs.
How to Take the Measurements
Accuracy depends on consistent measuring. Use a flexible tape, measure on bare skin, and keep the tape horizontal and snug without squeezing.
- Neck: just below the larynx (Adam's apple), tape sloping slightly down to the front.
- Waist: at the navel for men; at the narrowest point for women.
- Hips (women): at the widest point of the buttocks.
- Height: standing straight, without shoes.
- Measure in the morning before eating for consistency, and re-measure 2–3 times and average.
Body Fat Percentage Categories
Healthy body fat ranges differ for men and women — women naturally carry more essential fat. The table below shows common categories. Where you want to be depends on your goals: athletic performance, general fitness, or health.
Fat Mass and Lean Body Mass
If you enter your weight, the calculator splits it into fat mass (your weight x body fat %) and lean body mass (everything else — muscle, bone, organs, water). Tracking lean mass is useful when dieting: the goal is to lose fat while keeping lean mass, which a scale alone can't tell you.
How Accurate Is It?
The US Navy method is a reasonable estimate — typically within a few percentage points of more advanced methods — but it is not as precise as a DEXA scan or hydrostatic weighing. Its real strength is consistency: measured the same way over time, it tracks your trend reliably, which is what matters for progress.
Body Fat Percentage Categories
| 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%+ |