Body Fat Calculator Widget

How it works

The US Navy method estimates body fat from a few tape measurements and height; Hodgdon and Beckett derived it at the Naval Health Research Center in 1984 against underwater weighing. In metric mode the widget uses the same centimetre formula as the A2Z Body Fat Calculator (a body-density equation converted with Siri's 495/density - 450); in imperial mode it uses the inch equations the US Department of Defense adopted, so each unit system runs its own published formula rather than a conversion. The result is placed in the American Council on Exercise ranges. If weight is entered, fat and lean mass are shown, and if age is entered too, a BMI-based estimate (Deurenberg, 1991) is added and labelled as the rougher figure it is. Measurements that would make the formula meaningless (waist not larger than neck) or give an implausible result are refused with an explanation.

Calculation method

• Men (cm): %BF = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450
• Women (cm): %BF = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450
• Men (in): %BF = 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76
• Women (in): %BF = 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387
• Optional BMI-based estimate (Deurenberg 1991): 1.2 x BMI + 0.23 x age - 10.8 x sex (1 men, 0 women) - 5.4
• ACE ranges, men: essential 2-5%, athletes 6-13%, fitness 14-17%, average 18-24%, obese 25%+; women: 10-13%, 14-20%, 21-24%, 25-31%, 32%+; all percentages shown to 1 decimal place

Worked examples

An estimate for general information only - not medical advice. Talk to a doctor or registered dietitian about your health.

Limitations

• A regression estimate from circumferences, not a measurement; it cannot replace DEXA, underwater weighing or skinfold testing by a trained assessor.
• Validated on adult military personnel; accuracy for older adults, children, pregnancy and people at the extremes of body fat is lower.
• The ACE categories are fitness-industry norms, not diagnostic cut-offs.

Where publishers use it

• Strength and physique coaches tracking clients' progress between check-ins
• Fitness blogs explaining why body composition matters more than scale weight
• Gym websites offering a no-equipment alternative to skinfold or scan appointments
• Military and police fitness preparation sites, where the Navy tape method is familiar

Questions

Sources

1. Prediction of percent body fat for U.S. Navy women from body circumferences and height (Hodgdon & Beckett, report 84-29) - Naval Health Research Center, San Diego, 1984 (DTIC ADA146456) . Women's circumference equation
2. Prediction of percent body fat for U.S. Navy men from body circumferences and height (Hodgdon & Beckett, report 84-11) - Naval Health Research Center, San Diego, 1984 . Men's circumference equation
3. Development of the DoD body composition estimation equations (Hodgdon & Friedl) - Naval Health Research Center (DTIC ADA370158) . Inch versions: 86.010 / 70.041 / 36.76 (men) and 163.205 / 97.684 / 78.387 (women)
4. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas (Deurenberg, Weststrate, Seidell) - British Journal of Nutrition 65(2):105-114, 1991 . BMI-based estimate
5. Body fat percentage: charting averages in men and women - American Council on Exercise . ACE average ranges (men 18-24%, women 25-31%); full category table from the ACE Personal Trainer Manual

Cite or recommend this tool

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A2Z Tools Body Fat Calculator
https://a2z.tools/body-fat-calculator

<a href="https://a2z.tools/body-fat-calculator">A2Z Tools Body Fat Calculator</a>

[A2Z Tools Body Fat Calculator](https://a2z.tools/body-fat-calculator)

Body Fat Calculator by A2Z Tools - https://a2z.tools/body-fat-calculator