How to Calculate Body Fat Percentage
Body fat percentage is the proportion of your total body weight that is made up of fat tissue. Unlike BMI which only considers height and weight, body fat percentage gives a more accurate picture of your body composition — distinguishing between fat mass and lean mass which includes muscle, bone and organs.
Our calculator uses the US Navy Body Fat Formula — one of the most widely used and accurate methods for estimating body fat percentage without expensive equipment. It requires simple circumference measurements that anyone can take at home.
US Navy Body Fat Formula:
Men:
BF% = 495 / (1.0324 - 0.19077 × log10(waist - neck) + 0.15456 × log10(height)) - 450
Women:
BF% = 495 / (1.29579 - 0.35004 × log10(waist + hip - neck) + 0.22100 × log10(height)) - 450
All measurements in centimeters
How to Take Accurate Measurements
- Height — stand straight against a wall, measure from floor to top of head
- Neck — measure just below the larynx (Adam's apple), tape perpendicular to neck axis
- Waist — measure at the narrowest point, usually at or just above the navel
- Hips (women only) — measure at the widest point of the hips and buttocks
- Take all measurements in the morning before eating for most consistency
- Take each measurement twice and use the average for accuracy
Body Fat vs BMI — Which Is Better?
BMI is easier to calculate but has significant limitations — it cannot distinguish between muscle and fat. A muscular athlete may have a high BMI but low body fat. Body fat percentage is a more accurate measure of health and fitness. However both metrics together give a more complete picture than either alone.
⚠️ Medical Disclaimer: This body fat calculator provides estimates for informational purposes only. Results may vary from clinical measurements. Always consult a qualified healthcare professional for accurate body composition assessment and health advice.
Frequently Asked Questions
What is a healthy body fat percentage? +
Healthy body fat ranges differ by gender. For men, 10-20% is generally considered healthy, with athletes at 6-13% and fitness enthusiasts at 14-17%. For women, 18-28% is healthy, with athletes at 14-20% and fitness at 21-24%. Essential fat for basic body functions is 2-5% for men and 10-13% for women.
How accurate is the US Navy body fat formula? +
The US Navy formula is accurate within 3-4% for most people when measurements are taken correctly. It is considered one of the most practical field methods for estimating body fat. For the most accurate results take measurements multiple times and use the average. DEXA scans are the gold standard but require medical equipment.
How do I reduce my body fat percentage? +
To reduce body fat percentage combine a moderate calorie deficit with regular exercise. Strength training preserves and builds lean muscle while cardio burns additional calories. Aim to lose 0.5-1% body fat per month for sustainable results. Crash diets cause muscle loss which can increase body fat percentage even if the scale drops.
What is lean body mass? +
Lean body mass is everything in your body except fat — muscles, bones, organs, water and connective tissue. It is calculated as Total Body Weight minus Fat Mass. Preserving lean body mass is crucial during weight loss because muscle burns more calories at rest and maintains metabolic rate.
Can body fat percentage be too low? +
Yes. Essential body fat is necessary for basic physiological functions including hormone production, organ protection and temperature regulation. For men, below 5% is dangerously low. For women, below 10-13% can cause hormonal disruption, bone loss and serious health complications. Even competitive bodybuilders only maintain very low body fat for brief competition periods.