Body Fat Percentage Estimator
Estimate body fat percentage from tape measurements using the US Navy circumference method.
Formula
US Navy circumference method — a logarithmic fit to tape measurements
Tips
- The Navy method is accurate to roughly ±3.5 percentage points against a DEXA scan, and can be further out for very lean or very heavy people. Treat the range as the real answer, not the single figure.
- Measure at the same time of day, unclothed at the measurement point, with the tape snug but not compressing. Small differences in tape placement move the result more than most real change does.
- Waist-to-height ratio is a simpler measure with better evidence behind it for health risk. Below 0.5 is the usual guidance, and it needs only two measurements.
- Body fat percentage is one descriptive number among many. It says nothing about fitness, strength, blood markers or how you feel, and a single reading says nothing at all about a trend.
Frequently asked questions
What is a healthy body fat percentage?
Ranges published by fitness organisations vary widely and are not clinical thresholds. Essential fat is roughly 3% for men and 12% for women, below which health is compromised. Beyond that, there is no single healthy figure — it depends on age, sex, genetics and context. A clinician can interpret it alongside things that matter more.
Why does my result differ from a smart scale?
Bioelectrical impedance scales estimate from body water, which swings with hydration, food, exercise and time of day. Neither method is a direct measurement. Both are more useful for tracking a direction over months than for a single number today.