How it is calculated
Men: %BF = 495 ÷ (1.0324 − 0.19077·log10(waist − neck) + 0.15456·log10(height)) − 450 Women: %BF = 495 ÷ (1.29579 − 0.35004·log10(waist + hip − neck) + 0.22100·log10(height)) − 450All in centimetres. Waist at the navel for men and narrowest point for women; hips at the widest point.
| 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%+ |
Worked example
A 178 cm man with a 38 cm neck and 90 cm waist: body fat ≈ 20.1%, in the “average” range.
Frequently asked questions
How accurate is it?
Typically within 3–4%; it is good for tracking change over time if you measure consistently.
What is more accurate?
DEXA, then underwater weighing; bioimpedance scales are less accurate and affected by hydration.
Is body fat more useful than weight?
Usually yes — it reflects body composition better than weight or BMI.