Body Fat Calculator
All you need is a tape measure. The US Navy method estimates body fat from your neck, waist, and height.
How it works
The US Navy developed this formula to estimate body fat from circumference measurements. For men it uses waist minus neck against height; for women, waist plus hip minus neck. The math runs on logarithms, but the inputs are just three or four tape measurements.
Tracking it over time
A single reading matters less than the trend. Measure every 2-4 weeks, same time of day, same conditions. If the waist number falls while your lifts hold steady, you're losing fat and keeping muscle — exactly what a cut should do.
FAQ
How accurate is the Navy method?
Studies put it within about 3-4% of a DEXA scan for most people. It can read high on very muscular lifters and low on very lean ones — but measured the same way every time, the trend is reliable.
How do I measure correctly?
Neck: just below the Adam's apple, tape sloping slightly down at the front. Waist: at the navel for men, at the narrowest point for women, relaxed — don't suck in. Hips (women): at the widest point. Keep the tape snug but not compressing.
What's a healthy body fat percentage?
For men, roughly 10-20% is a fit range with essential fat around 3%. For women, roughly 18-28% with essential fat around 12%. Visible abs typically show up near 10-12% for men and 16-20% for women.
How fast can I lose body fat?
A sustainable cut drops about 0.5-1% of bodyweight per week, which works out to roughly 1% of body fat per month for most people. Faster than that usually costs muscle.
Why does my number differ from my smart scale?
Bio-impedance scales swing several percent with hydration, food, and time of day. Tape measurements are more stable. Whichever you use, use only one method and track the trend.
Related
Skip the tape measure
Buffro's AI physique scanner estimates your body fat from one photo — plus a physique score and the exact muscles to bring up.