Body Fat Calculator
A tape measure and this page get you within a few points of a proper body-composition scan — far more informative than what the bathroom scale alone can tell you.
How to measure properly
The formula is only as good as the tape work. Do all of it in the morning, before eating, standing relaxed:
- Neck: just below the larynx, tape sloping slightly down at the front.
- Waist: across the navel for men; at the narrowest point for women. Do not suck in, and measure at the end of a normal breath out.
- Hips (women): the widest point of the buttocks.
Measure each site twice and use the average. A single centimetre of sloppiness at the waist moves the result by more than a full percentage point.
What the categories mean
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletic | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Above average | 25%+ | 32%+ |
Accuracy, honestly stated. The Navy method typically lands within 3–4 percentage points of a DEXA scan. That is more than good enough to track a direction over months, and not precise enough to argue about a single point.
Why this beats the scale
Scale weight bundles muscle, fat, water, food and glycogen into one figure. Someone who trains hard for eight weeks can lose 4 kg of fat, gain 2 kg of muscle and see the scale barely move — a genuine success that looks like failure.
Track body fat percentage and waist measurement monthly, in the same conditions. When those fall while your lifts hold or improve, everything is working, whatever the scale says.
Frequently asked questions
How often should I measure?
Every two to four weeks. Body composition changes slowly, and measuring more often just adds noise you will misread as progress or failure.
Why is this different from my smart scale?
Bioimpedance scales send a small current through the body and are heavily affected by hydration, food and even skin temperature. Neither is exact; pick one method and stay with it.
What body fat should I aim for?
Health-wise, roughly 10–20% for men and 18–28% for women is a sensible band. Lower is a performance or aesthetic choice with real costs in energy and hunger.