Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy Method with simple body measurements.
How the Body Fat Calculator Works
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 provides a more accurate picture of body composition. Two people with the same BMI can have very different body fat levels — a muscular athlete and a sedentary office worker, for example. Knowing your body fat percentage helps you set more meaningful fitness goals and better assess health risks associated with excess adiposity.
This calculator uses the U.S. Navy Method, developed by Hodgdon and Beckett at the Naval Health Research Center in 1984. The method uses circumference measurements to estimate body density, then converts to body fat percentage. The formulas are: for men, BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76; for women, BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387. All measurements are in centimeters.
For example, consider a man who is 178 cm tall with a 85 cm waist and 38 cm neck. His body fat would be: 86.010 × log₁₀(85 − 38) − 70.041 × log₁₀(178) + 36.76 = 86.010 × 1.672 − 70.041 × 2.250 + 36.76 ≈ 143.8 − 157.6 + 36.76 ≈ 17.0%. This places him in the "Fitness" category for men, indicating a healthy and active body composition.
The classifications used in this calculator are based on the American Council on Exercise (ACE) categories. For men: Essential Fat (2–5%), Athletes (6–13%), Fitness (14–17%), Average (18–24%), and Obese (25%+). For women: Essential Fat (10–13%), Athletes (14–20%), Fitness (21–24%), Average (25–31%), and Obese (32%+). Women naturally carry more essential fat due to reproductive functions and hormonal differences.
While the Navy Method is convenient and reasonably accurate (within 1–3% of hydrostatic weighing for most people), it has limitations. It may be less accurate for very muscular individuals, the elderly, or those with unusual body proportions. More precise methods include DEXA (Dual-Energy X-ray Absorptiometry), hydrostatic (underwater) weighing, and air displacement plethysmography (Bod Pod). For clinical purposes, these laboratory methods are preferred, but the Navy Method remains an excellent free screening tool for the general population.