Body Fat Calculator

The scale gives you one number and hides everything that matters. This calculator splits that number into fat and muscle. Pick your sex and units, enter a few tape measurements, add your weight, and you get an estimated body fat percentage plus your fat mass, lean mass, and a category band. No calipers, no scan, no sign-up.

What the Navy method does

It uses the US Navy circumference formula. Men need neck, waist, and height. Women add a hip measurement, because fat distribution differs and the extra site sharpens the estimate. The math runs in inches, so the calculator converts your centimetres for you before it computes.

This is an estimate, not a DEXA scan. Expect it to land within a few points of a lab read for most people. The value is consistency. Measure the same way each time and the trend it shows you is honest, even if the absolute figure is off by a point or two.

How to measure well

The result is only as good as your tape work. Pull the tape snug against skin without compressing it. Measure the neck below the larynx, the waist at the navel, and the hip at the widest point. Breathe normally and read at the end of a relaxed exhale.

Take each measurement twice and use the average. A centimetre of slack on the waist can swing your reading by more than a percentage point, so a careful tape beats a guessed body fat number every time.

Reading your result

The category band tells you where you sit, from essential through athletic, fitness, average, and high. Lean mass is the more useful figure for training. It is the weight you want to protect in a cut and build in a gain. If you drop scale weight but hold lean mass, the diet is working.

To rate that lean mass against your height, run the FFMI calculator. To track only the muscle side as you train, use lean body mass. When you are ready to build a plan that adds muscle while trimming fat, read the body recomposition guide.