Nutrinaut Tool
Body Fat % (US Navy Method)
Estimate body fat percentage from tape measurements. Fast, cheap, and surprisingly useful when tracked over time.
What this tool does
Uses the U.S. Navy tape formula to estimate body-fat percentage from simple body measurements you can repeat at home in minutes.
Who and when to use it
- People who want body-composition trend tracking without expensive scans.
- Anyone running a cut/recomp and needing feedback beyond scale weight.
- Users comparing monthly progress while keeping hydration/timing consistent.
Step-by-step usage
- Select sex and preferred units.
- Measure height, neck, waist (and hip for women) with a relaxed tape.
- Submit to generate estimated body-fat percentage and category.
- Repeat weekly under similar conditions and track trend direction.
Example interpretation
If you move from 24.8% to 23.9% over 4 weeks while body weight stays similar, that usually suggests composition improvement, not “no progress.”
FAQ
Is this as accurate as DEXA?
No. DEXA is more precise. Navy method is a convenient trend tool, not a lab-grade diagnosis.
How often should I measure?
Once per week is usually enough; daily readings add noise.
What causes bad readings?
Inconsistent tape position, pulling too tight, different hydration states, and different measurement times.
Should I track waist alone instead?
Waist is useful, but combining waist + neck + height gives a richer composition estimate.
