단계별 지침
Take Your Measurements
Measure your neck at its widest point (just below the larynx). Measure your waist at the level of your belly button. If you are female, measure your hips at their widest point. Ensure the tape is parallel to the floor.
Calculate the Logarithms
Use a scientific calculator to find the log10 of your measurement sums. This logarithmic scaling is what allows the simple tape measurements to approximate body density.
Apply the Formula
Input your values into the corresponding gender-specific formula. Multiply the logs by the provided constants and add/subtract the final adjustment factor to get your percentage.
Interpret Your Results
Compare your result to healthy ranges. Generally, 14-24% is considered healthy for men, while 21-31% is standard for women. Consult a professional if your results fall outside these ranges.
Understanding the Navy Body Fat Method
The US Navy method is a widely recognized, practical way to estimate body fat percentage using only a tape measure and a calculator. While it isn't as precise as a DEXA scan, it is an excellent tool for tracking long-term progress.
Prerequisites
- A flexible cloth measuring tape.
- A calculator.
- A mirror to ensure your tape is level.
The Anatomy of the Formula
The formula relies on measuring the circumference of your neck and waist (and hips for women) to estimate body volume.
For Men:
Body Fat % = 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76
For Women:
Body Fat % = 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387
(Note: All measurements are in inches. log10 is the base-10 logarithm found on scientific calculators.)
Worked Example
Imagine a man who is 70 inches tall with a 36-inch waist and a 16-inch neck.
- Subtract neck from waist: 36 - 16 = 20.
- Calculate log10(20) ≈ 1.301.
- Calculate log10(70) ≈ 1.845.
- Plug into formula: (86.010 * 1.301) - (70.041 * 1.845) + 36.76.
- Result: 111.89 - 129.22 + 36.76 ≈ 19.4% body fat.
Common Pitfalls
- Tape Tension: Pull the tape snug against the skin, but do not compress the fat tissue.
- Measurement Location: Measure the waist at the navel (belly button) for the Navy method, not the narrowest part of the waist.
- Consistency: Always measure at the same time of day, ideally in the morning before eating.
When to Use a Calculator
Manual calculation is great for understanding the math, but online calculators are better for avoiding rounding errors during the logarithmic steps. Use a calculator when you want to track multiple entries over months to ensure your data points remain consistent.