Body Fat Calculator
Estimate body fat percentage using the U.S. Navy method from neck, waist, and hip measurements.
Medical Disclaimer
This calculator provides estimates only and is not a substitute for professional body composition analysis (e.g., DEXA scan, hydrostatic weighing). Results may vary significantly based on individual factors. Consult a healthcare professional for accurate assessment.
What This Calculator Does
This body fat calculator estimates body fat percentage using the U.S. Navy method (tape measurements) or BMI-based Deurenberg formula. It categorizes results by fitness level and provides lean vs. fat mass breakdown.
The Formula
The U.S. Navy method uses circumference measurements and height with a logarithmic formula. The BMI-based Deurenberg formula uses BMI, age, and sex but is less accurate. Both are screening estimates.
Step-by-Step Example
Choose method
Navy method (more accurate, requires tape measure) or BMI-based (only needs height, weight, age).
Take measurements
Navy: measure neck, waist (at navel), and hips (females) at the widest point. Use a flexible tape measure.
Enter data
Input measurements, height, sex, and (for BMI method) weight and age.
Review results
Body fat %, fitness category, and lean vs. fat mass estimates.
Real-World Use Cases
Fitness Progress
Track body composition changes over time as you train and adjust nutrition.
Goal Setting
Set realistic body fat targets based on the category reference table.
Health Screening
A more informative metric than BMI alone for assessing body composition.
Common Mistakes to Avoid
Taking measurements at inconsistent times. Measure first thing in the morning before eating for consistency.
Pulling the tape measure too tight or too loose. It should sit snugly against the skin without compressing tissue.
Expecting lab-grade accuracy from a tape-measure formula. These estimates can be off by 3-4%.
Frequently Asked Questions
Accuracy and Disclaimer
MEDICAL DISCLAIMER: This calculator provides estimates only and is NOT a substitute for professional body composition analysis (e.g., DEXA scan, hydrostatic weighing). Results may vary significantly based on individual factors including hydration, time of day, and measurement technique. Consult a healthcare professional for accurate body composition assessment.
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