The Body Fat Percentage Calculator measures body fat percentage using the proven US Navy method.
Enter your height, neck circumference, and waist circumference (plus hip circumference for women) to get your body fat percentage. Results are categorized from essential fat to obese with a visual gauge.
Disclaimer: Results are estimates. The most accurate method is a DEXA scan. Consult a doctor for a health evaluation.
Calculator information
📋 How to use this calculator
- Choose your sex (male or female) because the formulas differ.
- Enter your height in centimeters.
- Measure and enter your neck circumference just below the larynx (Adam's apple) in centimeters.
- Measure and enter your waist circumference at navel level (for men) or at the narrowest point (for women) in centimeters.
- For women, also add the hip circumference at its widest point.
- Click Calculate to see the body fat percentage and the category (essential, athlete, fitness, average, obese).
- Tip: measure in the morning before eating, use a non-stretch measuring tape, and do not pull it tight.
🧮 Body Fat Percentage Method (US Navy)
Men: %BF = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450. Women: %BF = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450.
- waist, neck, hip, height in centimeters
- log10 = base-10 logarithm
- Result is in percent (%)
Categories per the American Council on Exercise (ACE): Men - essential 2-5%, athlete 6-13%, fitness 14-17%, average 18-24%, obese 25%+. Women - essential 10-13%, athlete 14-20%, fitness 21-24%, average 25-31%, obese 32%+.
💡 Worked example: Calculating body fat percentage for an adult man
Given:- Sex: male
- Height: 170 cm
- Neck circumference: 38 cm
- Waist circumference: 85 cm
Steps:- Waist-neck difference = 85 - 38 = 47.
- log10(47) ~ 1.672; log10(170) ~ 2.230.
- Denominator = 1.0324 - 0.19077 x 1.672 + 0.15456 x 2.230 = 1.0324 - 0.3190 + 0.3447 = 1.0581.
- %BF = 495 / 1.0581 - 450 = 467.86 - 450 = 17.86%.
Result: Body fat percentage ~ 17.9%, in the fitness category (healthy and fit).
❓ Frequently asked questions
What is the difference between body fat percentage and BMI?
BMI only compares weight and height without separating fat from muscle, so muscular athletes can be classified as overweight even when healthy. Body fat percentage measures the proportion of fat to total body mass, giving a more accurate read on body composition. Ideally both numbers are reviewed together with waist circumference.
How accurate is the US Navy method?
The US Navy method is accurate within 3-4% compared to DEXA scans (the gold standard). Accuracy depends on careful tape-measure technique. For higher accuracy use bioelectrical impedance (BIA) or DEXA. For tracking trends, the US Navy method is sufficient and free.
What is an ideal body fat percentage?
According to the American Council on Exercise, the healthy range is 14-24% for men and 21-31% for women. Athletes can be lower; above 25% (men) or 32% (women) is classified as obese. Essential fat minimums are 3% (men) and 12% (women), needed for hormonal and organ function.
How can I reduce body fat percentage healthily?
Combine a moderate calorie deficit (300-500 kcal/day), strength training to preserve muscle mass, and light-to-moderate cardio. Target 0.5-1 kg of loss per week to preserve muscle. The CDC recommends not dropping below 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision.
Should women have a higher body fat percentage than men?
Yes - physiologically women need more body fat (essential minimum 12%) to support menstruation, pregnancy, and lactation. This fat is stored in the breasts, hips, and thighs. If a woman's body fat drops below 12-15%, it can cause amenorrhea and hormonal disruption.
📚 Sources & references
Last updated: May 11, 2026