Body Fat Calculator
Estimate your body fat percentage using the US Navy method.
How It Works
This calculator uses the US Navy circumference method, which estimates body fat percentage from a few tape-measure inputs. It's free, requires no callipers, and is accurate to within ±3-4% for most adults.
Formulas
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
Body Fat Categories (American Council on Exercise)
Essential fat: men 2-5%, women 10-13%. Athletes: men 6-13%, women 14-20%. Fitness: men 14-17%, women 21-24%. Average: men 18-24%, women 25-31%. Obese: men 25%+, women 32%+.
FAQ
How accurate is the US Navy method?
It typically falls within 3-4% of more precise methods like DEXA scans, making it one of the best free options.
Where do I measure?
Neck: just below the larynx. Waist: at the navel for men, narrowest point for women. Hip: at the widest part. Stand relaxed, don't pull the tape tight.
Is my data stored?
No. Everything runs in your browser — nothing is uploaded.
Should I use this as a medical diagnosis?
No. Talk to a doctor for medical advice. This is an educational estimate.
Why does the formula differ for men and women?
Women carry more essential body fat and the distribution differs, so the formula adds a hip measurement for accuracy.
Love using BreezyTools?
Go Pro for an ad-free experience, priority features, and support independent development — for less than a coffee a month.