How to calculate Body Fat Calculator?

The US Navy method estimates body fat percentage from simple circumference measurements and height. Different formulas are used for men and women.

Key formula (US Navy): Men: 86.010 * log10(waist - neck) - 70.041 * log10(height) + 36.76 Women: 163.205 * log10(waist + hip - neck) - 97.684 * log10(height) - 78.387

Using the Body Fat Calculator calculator: an example

Example values: Male, height 180 cm, weight 80 kg, neck 40 cm, waist 90 cm.

Step-by-step calculation:

1. Compute the difference: waist - neck = 90 - 40 = 50 cm, then log10(50) ≈ 1.699.
2. Compute log10(height): log10(180) ≈ 2.255.
3. Plug into the men's formula: 86.010×1.699 − 70.041×2.255 + 36.76 ≈ 25.0% body fat (approximate).
4. Convert to masses: body fat mass ≈ 80 kg × 0.25 = 20.0 kg; lean body mass ≈ 80 − 20 = 60.0 kg.

Frequently Asked Questions

How accurate is the US Navy method?

It provides an estimate that is generally accurate for many people but can vary by about ±3–4 percentage points compared to gold-standard methods.

When should I take the circumference measurements?

Measure standing upright, relaxed, and after a normal exhale. Use the same landmarks each time for consistent tracking.

Do women need to measure hip circumference?

Yes. The hip measurement is required for the women's US Navy formula; it is not used in the men's formula.