Body Fat Calculator
Last updated: June 9, 2026Estimate body fat % with the Navy method.
The Body Fat Calculator estimates your body fat percentage using the U.S. Navy circumference method, so you only need a tape measure instead of calipers or a scan. Enter your height, neck, and waist (plus hips for women), pick inches or centimeters, and it returns your body fat percent and category for men or women instantly. Everything runs in your browser, free, with no sign-up and nothing uploaded.
Disclaimer: This calculator gives general estimates for informational purposes only and is not medical advice. Results vary by individual, measurement method and formula. Always consult a qualified healthcare professional before making decisions about your health, diet or fitness.
How to use Body Fat Calculator
The calculator turns a few tape measurements into a body fat estimate using the Navy's validated equation. Measure relaxed, breathe out normally, and keep the tape snug but not compressing your skin. Take each measurement twice and use the average for a steadier reading. Select your sex and units first, since men and women use different inputs and formulas.
Read the full guide: How to Calculate Body Fat Percentage (Navy Method)
- 1Choose your sex and your preferred units (inches or centimeters), then enter your height.
- 2Measure your neck just below the larynx and your waist at the navel; women also measure the hips at the widest point.
- 3Type each circumference into its field, taking the tape reading after a relaxed exhale for consistency.
- 4Read your estimated body fat percentage and its category, then re-measure and average if the number looks off.
No special equipment
A cloth tape measure is all you need, with no calipers, bioimpedance scale, or DEXA appointment required.
Sex-specific equations
Men are scored from waist and neck while women add hip circumference, matching the separate Navy formulas for each.
Instant category context
Your percentage is mapped to a descriptive range so you can see where it falls rather than reading a bare number.
Track body fat without a gym scan
Bioimpedance scales and DEXA scans cost money and access. With just a tape measure you can log your body fat percentage at home every few weeks, measuring under the same conditions each time so the trend line, not any single number, shows whether a cut or bulk is actually working.
Check Navy body composition standards
Service members and recruits use this same circumference method for the official tape test. Estimating your number beforehand shows roughly where you stand against your branch's body fat limits, helping you decide how much margin you have before an assessment without guessing or paying for outside testing.
Compare body fat for men and women
Because the calculator implements separate male and female equations, couples or training partners can each get an accurate reading from the correct formula. Women's inclusion of hip circumference reflects different fat distribution, so both people see a category suited to their physiology instead of a one-size estimate.
Set a fat-loss starting baseline
Before beginning a diet or training block, capture a baseline body fat percentage to define realistic goals. Knowing you are starting near 25 percent versus 18 percent reshapes target timelines, weekly deficits, and how aggressively you cut, giving you a concrete reference point to measure progress against later.
Body Fat Calculator — frequently asked questions
What formula does this calculator use?
It uses the Hodgdon-Beckett U.S. Navy equations. For men: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76. For women: 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387, with all lengths in inches.
How accurate is the Navy circumference method?
For most people it lands within about 3 to 4 percentage points of a DEXA or hydrostatic reading. It works from average body shapes, so very muscular, very lean, or unusually proportioned bodies may see larger deviations. Treat it as a quick, repeatable estimate rather than a clinical measurement.
Can I use centimeters instead of inches?
Yes. Switch the unit toggle and the calculator applies the metric form of the same Navy equation, so your result is identical whether you enter inches or centimeters. Just keep every field in one unit system at a time.
Where exactly do I measure my neck, waist, and hips?
Measure the neck just below the Adam's apple with the tape sloping slightly down at the front. Measure the waist horizontally at the navel for men, and at the narrowest point for women. Hips are measured at the widest part of the buttocks.
Is my measurement data kept private?
Yes. The entire calculation happens locally in your browser using JavaScript. Your height and circumference numbers are never sent to a server, stored, or shared, and nothing is uploaded at any point.
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