Body composition

Body Fat % Calculator

Estimate your body fat percentage using the US Navy method.

Biological sex:

Height (cm)

Neck (cm)

Waist circumference (cm)

What is body fat percentage?

Body fat percentage is the proportion of your total body weight made up of fat tissue. Unlike BMI, it distinguishes between fat mass and lean mass (muscle, bone, water). Essential fat is necessary for physiological functions; excess fat increases the risk of metabolic and cardiovascular disease.

How is it calculated?

The US Navy circumference method uses measurements of height, neck and waist (and hips for women) with a logarithmic formula developed by Hodgdon & Beckett (1984). It does not require specialised equipment — only a tape measure.

Formula

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)) − 450

⚠️ Limitations

The Navy method has a margin of error of ±3–4% compared to DEXA (gold standard). It is less accurate for people with atypical fat distribution or very low/high body fat levels.

FAQ

What is a healthy body fat percentage?

For men: 6–24% is generally healthy. For women: 16–30%. Athletes typically fall in the lower ranges of these brackets.

Is body fat percentage more useful than BMI?

Yes, for most people. Body fat percentage directly measures fat mass, making it more relevant for assessing health and fitness than BMI.

How do I reduce my body fat percentage?

A combination of caloric deficit, strength training (to preserve muscle) and adequate protein intake (1.8–2.2 g/kg) is the most effective approach.

How accurate is the Navy method compared to DEXA?

The Navy method has a margin of error of approximately ±3–4% compared to DEXA scanning. It is reliable enough for tracking trends over time.