Body Fat Calculator

1. Select Metric (cm/kg) or Imperial (in/lbs) units.
2. Choose your gender.
3. Enter your weight and height.
4. Measure and enter your neck circumference at its narrowest point.
5. Measure and enter your waist circumference at your navel.
6. For women: also enter your hip circumference at the widest point.
7. View your body fat %, fat mass, lean mass, and category.
8. Check the reference table to see where you fall among body fat categories.

What is Body Fat Percentage?

Body fat percentage is the proportion of your total body weight that consists of fat tissue. Unlike BMI, which only considers weight relative to height, body fat percentage distinguishes between fat mass and lean mass (muscle, bone, organs, and water). This makes it a far more accurate indicator of body composition and overall health. Two people can weigh the same and have the same BMI, but very different body fat percentages and very different health profiles. Tracking body fat percentage is especially valuable for athletes, strength trainers, and anyone focused on changing their body composition rather than simply losing or gaining scale weight.

How the US Navy Method Works

This calculator uses the US Navy body fat estimation method, developed by researchers Hodgdon and Beckett at the Naval Health Research Center. The method estimates body fat percentage using simple circumference measurements taken with a flexible tape measure, making it accessible without expensive lab equipment. The formulas are as follows:

Formula for Men:
Body Fat % = 495 / (1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height)) - 450

Formula for Women:
Body Fat % = 495 / (1.29579 - 0.35004 x log10(waist + hip - neck) + 0.22100 x log10(height)) - 450

All measurements must be in centimeters for the formula to produce correct results. This calculator automatically converts inches to centimeters when you select Imperial units. Your fat mass and lean mass are then derived from the body fat percentage applied to your total body weight.

Common Use Cases

• Assessing body composition when BMI does not tell the full story
• Tracking fat loss progress during a diet or training program
• Military and law enforcement fitness assessments (the US Navy uses this exact formula)
• Setting realistic body composition goals for cutting or bulking phases
• Monitoring health risks associated with excess visceral fat
• Comparing results over time using consistent measurement techniques

Body Fat Categories Explained

Healthy body fat ranges differ significantly between men and women because women carry more essential fat for reproductive and hormonal functions. For men, the categories are: Essential Fat (2 to 5%), Athletes (6 to 13%), Fitness (14 to 17%), Acceptable (18 to 24%), and Obese (25% and above). For women, the categories are: Essential Fat (10 to 13%), Athletes (14 to 20%), Fitness (21 to 24%), Acceptable (25 to 31%), and Obese (32% and above). Dropping below essential fat levels is dangerous and can cause organ damage, hormonal disruption, and other serious health consequences.

The US Navy method is accurate to within 3 to 4 percent of body fat compared to hydrostatic (underwater) weighing. For the best accuracy, take measurements at the same time of day, use consistent technique, and average two to three readings. The method is most reliable for individuals in the average body fat range and may be less precise for very lean or very overweight individuals. More advanced methods such as DEXA scans, hydrostatic weighing, and Bod Pod testing offer greater precision but require specialized equipment and are more expensive. Consult a healthcare professional if you need a clinical-grade assessment.

Related Health Tools

Pair your body fat reading with other metrics for a complete health picture. Check your weight classification with the BMI Calculator, find your target weight with the Ideal Weight Calculator, or plan your nutrition with the Calorie Calculator and Macro Calculator.