Body Fat Calculator
Body fat percentage tells you far more than scale weight — two people at 180 lbs can look completely different. The U.S. Navy method estimates it from a few tape measurements, no calipers or lab visit required.
Measure in the morning, relaxed — not flexed. Tape should be snug but not compressing skin. Accuracy is typically ±3–4%.
How to measure
- Neck: just below the Adam’s apple, tape flat.
- Waist: at the narrowest point (men) or natural waistline (women), relaxed — breathe out normally.
- Hip (women): at the widest point around the buttocks.
- Height: standing straight, no shoes.
The Navy formula
Women: 495 ÷ (1.29579 − 0.35004×log10(waist+hip−neck) + 0.22100×log10(height)) − 450
(all measurements in inches)
Developed for the U.S. Navy’s fitness assessments, this method correlates well with lab methods for most people and only needs a tape measure.
Frequently asked questions
How accurate is the Navy body fat method?
Usually within ±3–4% of lab methods like DEXA for average builds. It’s less reliable for very muscular or very lean individuals.
Where exactly do I measure my waist?
Men: around the navel at the narrowest point. Women: at the natural waistline, roughly an inch above the navel. Keep the tape level all the way around.
Should I measure flexed or relaxed?
Relaxed. Flexing or sucking in changes the reading. Measure in the morning before eating for consistency.
What’s a healthy body fat percentage?
Roughly 10–20% for men and 18–28% for women covers the healthy range for most adults, varying with age and goals.
Why does my result seem off?
The usual culprits: measuring over clothing, pulling the tape too tight, or inconsistent waist placement. Re-measure carefully and average two readings.