How to use the Body Fat & Ideal Weight
- Select your sex and enter height and weight.
- Measure your neck and waist (and hips for women) with a tape.
- See your body fat %, category, fat and lean mass, and ideal weight.
How to measure
- Neck: just below the larynx (Adam’s apple), tape sloping slightly down to the front.
- Waist: men at the navel; women at the narrowest point.
- Hips (women): at the widest point of the buttocks.
Measure on bare skin, relaxed, without pulling the tape tight. Take each measurement twice and use the average.
Body fat categories
| Category | Men | Women |
|---|---|---|
| Essential fat | 2–5% | 10–13% |
| Athletes | 6–13% | 14–20% |
| Fitness | 14–17% | 21–24% |
| Average | 18–24% | 25–31% |
| Obese | 25%+ | 32%+ |
Source: American Council on Exercise. The Navy method is usually within a few percent of lab methods such as DEXA.
Ideal weight formulas
Devine, Robinson, Miller and Hamwi formulas estimate ideal weight from height and sex. They were designed for medication dosing and population averages, not body composition — so treat them as a rough guide alongside the healthy BMI range.
Frequently asked questions
Why use body fat instead of BMI?
BMI cannot tell muscle from fat. Body fat percentage gives a better picture of body composition, especially for active people.
How often should I measure?
Every 2–4 weeks is enough to see trends. Measure at the same time of day for consistency.