Understanding your result
How it's calculated
This uses the US Navy circumference method, validated against underwater weighing:
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
Women: 163.205·log₁₀(waist+hip−neck) − 97.684·log₁₀(height) − 78.387
Measure at the navel (waist), just below the larynx (neck), and the widest point (hip, women). It's an estimate — accurate to within a few percent for most people, and great for tracking change over time.
⚕️ An estimate for information only, not a clinical measurement like a DEXA scan. Measurement technique affects accuracy. Not a diagnosis.
Questions
What's a healthy body fat percentage?
For men, roughly 10–20% is typically healthy (athletes lower); for women, ~18–28%. Essential fat is ~3–5% (men) and ~10–13% (women). Ranges vary by age.
How accurate is the Navy method?
It's usually within 3–4% of lab methods when measured carefully — good enough to track progress. For clinical precision, a DEXA scan is the gold standard.
Is this private?
Yes — all maths runs in your browser; nothing is uploaded.
Sources
Evidence-based · last reviewed July 2026