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Body Fat Calculator

Estimate body fat % using the US Navy circumference method.

Short answer

The Navy method uses waist, neck, height (and hip for women) to estimate body fat % within ±3% of a DEXA scan for most people.

Measurements

Sex

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Calculation method, coverage and version

Inputs used
Sex, Height (cm), Neck circumference (cm), Waist circumference (cm), Hip circumference (cm) — women only.
Calculation approach
The calculator applies the rules and assumptions described in “How it works” to the values you enter. Rounding can cause small differences from an official or provider calculation.
Coverage
Health & Wellbeing. UK nations, tax treatment, local rules and provider criteria can differ; check the official sources shown below before acting.
Content version
No page-specific review date is currently published. Treat the result as indicative and verify current rules independently.
Not included unless explicitly requested: personal circumstances not entered, provider discretion, future rule changes, professional fees and case-specific exceptions. Read the full calculator methodology.

How it works

The US Navy circumference formula uses log-transformed body measurements that correlate well with hydrostatic body fat measurement.

Worked example

Male, 175 cm, 38 cm neck, 85 cm waist → ≈ 17% body fat (Fitness range).

Who should use this

  • •People tracking fat loss
  • •Anyone whose BMI is misleading (very muscular)

Common mistakes

  • ×Measuring over clothing
  • ×Holding breath or sucking in waist
  • ×Measuring at the navel — use the narrowest point

Frequently asked questions

Is this more accurate than BMI?▾

For body composition yes — BMI doesn't distinguish fat from muscle.

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BMI Calculator →BMR Calculator →TDEE Calculator →