Body Fat Percentage Calculator
Estimate your body fat percentage from height, neck, waist and hip measurements with the US Navy method, and see your BMI, lean and fat mass, and FFMI side by side.
Body fat percentage calculator (US Navy method)
How the body fat calculator works
The US Navy circumference method (Hodgdon and Beckett, 1984) estimates body fat from tape measurements:
- 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
All in inches. A man 70 in tall with a 15 in neck and 34 in waist is about 17.5% body fat. Tape methods are typically within about 3 to 4 percentage points of lab methods like DEXA; measure in the morning, tape snug but not compressing, and average three readings.
BMI calculator (men and women)
BMI = 703 × weight (lb) ÷ height (in)². 180 lb at 5'10" is 25.8. The categories are the same for men and women: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30+ obesity (CDC). BMI doesn't distinguish muscle from fat, which is why body fat percentage and FFMI are shown alongside; this works as a BMI calculator male or BMI calculator women (and BMI index calculator) all in one. Children and teens use BMI-for-age percentiles from the CDC growth charts, not these adult cutoffs.
FFMI calculator
Fat-free mass index = lean mass (kg) ÷ height (m)², normalized to 1.8 m by adding 6.1 × (1.8 − height). Average untrained men are around 18 to 20 and women 15 to 17; above about 25 is rare without performance-enhancing drugs (Kouri et al., 1995). The example man has about 148 lb of lean mass and an FFMI of about 21.3 (21.4 normalized).
Also searched as: body fat calculator, BMI calculator men.
Common questions
How do I calculate body fat percentage?
With a tape: the US Navy formula uses height, neck and waist (and hips for women).
What is a healthy body fat percentage?
Roughly 14% to 24% for men and 21% to 31% for women (American Council on Exercise ranges).
Is BMI accurate?
It's a quick screening number; muscular people can show a high BMI with low body fat.
What is a good FFMI?
About 18 to 20 for average men; 22 to 25 is very muscular.
What BMI is overweight?
25 to 29.9; 30 or more is obesity.
Sources
- CDC: Adult BMI categories
- Hodgdon & Beckett (1984), Naval Health Research Center: Prediction of percent body fat for U.S. Navy men and women
- Kouri et al. (1995), Clin J Sport Med: Fat-free mass index in users and nonusers of anabolic steroids
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.