Body fat percentage is a far better measure of fitness than weight or BMI alone. Two people of the same weight and height can have completely different body compositions — one lean and athletic, the other carrying excess fat. Knowing your body fat percentage helps you set realistic fitness goals and track progress that the bathroom scale cannot show.

Our calculator uses the US Navy body fat method, developed by the Naval Health Research Center and used by the US military for decades to assess service members. It only requires a tape measure and basic measurements (neck, waist, and for women, hips) and is accurate within 3-4% of more expensive methods like DEXA scans for most people.

How the US Navy method works

For men, the formula is: 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. All measurements should be in inches.

These formulas are derived from large studies correlating tape measurements with hydrostatic weighing (the gold standard at the time). The waist measurement is taken at the navel level for men and at the narrowest point for women. Hip measurement is at the widest point. Neck is just below the larynx.

The method works because fat distributes predictably in adults — extra abdominal width relative to height and frame size strongly correlates with total body fat. It is most accurate for adults with average body proportions, somewhat less accurate for very lean athletes or very obese individuals.

Healthy body fat ranges

For men, body fat categories are: essential 2-5%, athletes 6-13%, fitness 14-17%, average 18-24%, obese 25%+. Most men should aim for 10-20% body fat for optimal health and appearance. Below 6% is hard to maintain and can affect hormones and immune function.

For women, the categories are higher because women naturally need more body fat for hormonal and reproductive health: essential 10-13%, athletes 14-20%, fitness 21-24%, average 25-31%, obese 32%+. Most women should aim for 18-28% for health and aesthetics.

These ranges are guidelines, not strict targets. Some athletes function well at the low end. Some healthy people have higher body fat with no negative health markers. Use body fat as one data point alongside how you feel, perform, and look.

Reducing body fat

Body fat reduction comes from a sustained calorie deficit combined with strength training to preserve muscle. Cardio helps create the deficit but is not strictly necessary — diet alone can lower body fat. The key is consistency: small daily deficits add up over months.

Realistic body fat loss is 1-2% per month for most people. Faster rates are possible briefly but usually involve muscle loss too, which is counterproductive. Focus on adequate protein (0.8-1g per pound of body weight), strength training 2-4 times per week, and a moderate calorie deficit of 300-500 calories below TDEE.

How to use this calculator

1. Measure your neck just below the larynx with the tape level.
2. Measure your waist at navel level (men) or narrowest point (women).
3. If female, measure your hips at the widest point.
4. Enter your gender, height, and the measurements.
5. Click Calculate to see your estimated body fat percentage and category.

Frequently asked questions