How this body fat calculator works
The calculator estimates adult body fat percentage from tape measurements using the Hodgdon-Beckett / U.S. Navy circumference method. Metric measurements are converted to inches before the selected equation is applied.
Measurement inputs and formula
The male formula group uses height, neck and waist: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. The female formula group uses height, neck, waist and hip: 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387.
Circumference equations are sensitive to measurement site, tape tension and posture. Use the same technique if you compare estimates over time.
What this tool does not include
This tool does not diagnose body composition, health status or eligibility for any program. It is not a DXA scan, hydrostatic weighing, Bod Pod test, medical assessment or professional anthropometric assessment.
This calculator is scoped to adults only and is not designed for children or teenagers, pregnancy, eating disorder contexts, body dysmorphia concerns, medical conditions, treatment decisions, dieting decisions, weight-loss decisions, sport eligibility or military eligibility.
Key terms and assumptionsFormula notes, key terms, source assumptions and limits used in this calculator.
- Formula source
- This calculator uses the Hodgdon-Beckett / U.S. Navy circumference equations and converts metric measurements to inches before calculation.
- Formula group
- The selected group chooses which equation is used. It is not a broader identity, health-status or eligibility assessment.
- Measurement sensitivity
- Small differences in measurement site, posture and tape tension can change the estimate.
- Adult-only scope
- This calculator is scoped to adults and is not designed for children or teenagers, pregnancy, eating disorder contexts, body dysmorphia concerns, medical conditions or official eligibility decisions.
- No categories or advice
- This calculator does not show body-fat category bands and does not provide treatment, dieting, weight-loss, sport or military guidance.
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FAQs
What formula does this body fat calculator use?
This calculator uses the Hodgdon-Beckett / U.S. Navy circumference method. The male formula group uses 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. The female formula group uses 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387.
Is this a clinical body composition measurement?
No. It is a tape-measure formula estimate and not a clinical measurement such as DXA, hydrostatic weighing or a medical assessment.
Why does measurement technique matter?
Circumference formulas are sensitive to where and how measurements are taken, including tape tension, posture and measurement site.
Why does the female formula use hip measurement?
The selected female formula group includes hip circumference in that equation. The male formula group does not use hip measurement.
Does this calculator give body fat categories?
No. This calculator does not show body-fat category bands because category wording would need a separate reviewed source and wording plan.
Can children or teenagers use this calculator?
No. This calculator is scoped to adults and is not designed for children or teenagers.
Is this suitable during pregnancy?
No. This calculator is not designed for pregnancy.
Can I use this for military or sport eligibility?
No. This tool is a general estimate and not an official eligibility assessment for military, sport, workplace or other programs.