ShredXNeck
Measure just below the Adam's apple, with the tape sloping slightly down toward the front.
US Navy method · FreeBody fat calculator.
Body fat calculator.
Tape measure, 30 seconds.
Enter your height, neck, and waist to calculate your body fat percentage with the US Navy formula. Your result updates as you type.
- Instant result, no sign-up
- Works for men and women
- US or metric units
YOUR BODY FAT
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Fat mass
Lean mass
Watch this number drop.Track your body fat weekly with photo scans in ShredX.
No tape? Scan a photo instead
How to measure for the body fat calculator
Use a soft tape measure against bare skin. Keep it level and snug without pressing in. Measure twice and use the average.
Waist
Men: around the navel. Women: at the narrowest point. Breathe out normally and relax.
Hips (women)
Measure around the widest part of the hips and buttocks, with feet together.
The US Navy body fat formula
The Navy method estimates body fat from circumference measurements and height. With measurements in inches:
| 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 |
The calculator converts metric measurements to inches before applying the formula.
Body fat percentage chart
Compare your result with the American Council on Exercise (ACE) categories.
| Category | Men | Women | What it looks like |
|---|---|---|---|
| Essential fat | 2–5% | 10–13% | Stage-lean, extreme definition |
| Athletic | 6–13% | 14–20% | Visible six-pack and obliques |
| Fit | 14–17% | 21–24% | Ab outline, flat stomach |
| Average | 18–24% | 25–31% | Little ab definition |
| Above average | 25%+ | 32%+ | No visible abs |
More free tools
Frequently asked questions
How do I calculate body fat percentage at home?
Use a soft tape measure. Measure your neck, your waist, and (for women) your hips, then enter them with your height. The calculator uses the US Navy formula, the same method the military uses for its body fat standards.
How accurate is the Navy body fat calculator?
It is most useful when you measure the same way each time: same spot, same time of day, tape snug but not tight. Take each measurement twice and use the average.
Where do I measure my waist?
Men measure around the navel. Women measure at the narrowest point of the waist. Keep the tape level and relax your stomach.
What is a healthy body fat percentage?
For men, 14 to 24 percent is the fit and average range. For women, it is 21 to 31 percent. Visible abs usually start below about 13 percent for men and 20 percent for women.
Is there a faster way than measuring?
Yes. The ShredX body fat scanner estimates your body fat from one photo in a few seconds, with no tape measure.
Measure less.
Scan more.
Track your body fat and ab definition every week with ShredX.