Body Fat Percentage Calculator
Measure fat vs muscle composition using the US Navy formula — more accurate than BMI alone. Uses simple body measurements, no gym equipment needed.
ⓘ How to measure: Use a flexible tape. Neck = below larynx. Waist = at navel (men) / narrowest point (women). Hip = widest point of buttocks (women only). Breathe out normally before measuring.
Body Fat Category
ACE StandardsWhat is the Body Fat Calculator?
The Body Fat Calculator estimates your body fat percentage using the US Navy method, which requires simple tape measurements of your waist, neck, and height (and hip for women). Unlike BMI, which only uses height and weight, body fat percentage tells you what proportion of your total body mass is fat tissue versus lean mass (muscle, bone, and organs). This distinction is clinically important — two people with the same BMI can have very different body compositions. Athletes may have a high BMI but low body fat, while sedentary individuals may appear normal weight yet carry excess fat. Knowing your body fat percentage helps you set realistic fitness goals, track progress accurately, and understand your true health status beyond the scale.
How to Use the Body Fat Calculator
- 1. Select your unit system (metric cm or imperial inches) and gender.
- 2. Enter your height, waist circumference (measured at the narrowest point for men, at the navel for women), and neck circumference (measured just below the larynx).
- 3. Women should also enter their hip circumference (measured at the widest point).
- 4. Click "Calculate Body Fat" to see your body fat percentage, fat mass, lean mass, and your ACE fitness category.
Formula Used
Women: %BF = 495 / (1.29579 − 0.35004 × log10(waist + hip − neck) + 0.22100 × log10(height)) − 450
All measurements in centimetres. The US Navy formula uses body circumferences as proxies for fat distribution. It has a margin of error of approximately ±3–4% compared to DEXA scan, making it one of the most accessible and reasonably accurate field methods available. Example: Male 180cm tall, 90cm waist, 38cm neck → approximately 20% body fat.
Frequently Asked Questions
What is a healthy body fat percentage?
For men, essential fat is 2–5%, athletes range 6–13%, fitness level is 14–17%, and acceptable is 18–24%. For women, essential fat is 10–13%, athletes 14–20%, fitness level 21–24%, and acceptable 25–31%. Body fat above 25% (men) or 32% (women) is generally classified as obese.
How accurate is the US Navy body fat method?
The US Navy method is accurate to within approximately ±3–4% when measurements are taken correctly. It is more meaningful than BMI for body composition assessment. For highest accuracy, use a flexible tape measure, measure at the anatomically correct landmarks, and take 2–3 readings to average out variation.
What is the difference between BMI and body fat percentage?
BMI is a simple height-to-weight ratio that does not distinguish fat from muscle. A muscular athlete can have a high BMI but very low body fat. Body fat percentage measures the actual proportion of fat in your body, making it a more clinically relevant metric for assessing obesity-related health risks.
How can I reduce my body fat percentage?
To reduce body fat: maintain a moderate calorie deficit of 300–500 kcal/day, consume adequate protein (1.6–2.2g per kg body weight) to preserve muscle, combine resistance training 3–4 days per week with cardio, prioritise sleep (7–9 hours), and stay consistent over months rather than weeks. Crash dieting loses muscle as well as fat.