This Body Fat Calculator helps you estimate your body fat percentage using two common methods: the U.S. Navy Method and the BMI Method. Understanding your body fat percentage is important because it gives a clearer picture of your overall health and fitness beyond just your weight. By entering a few simple measurements like your age, gender, height, and body circumferences, you’ll get a detailed report showing your estimated body fat, fat mass, lean mass, and how you compare to ideal body fat ranges for your age and gender. This information can guide you in making healthier lifestyle choices and tracking your fitness progress.

The American Council on Exercise (ACE) Body Fat Categorization

Jackson & Pollock Ideal Body Fat Percentages by Age

Body Fat, Overweight, and Obesity — Key Points

• Adipose tissue (Body Fat): stores lipids (energy), produces hormones, cushions, and insulates the body.

• Essential fat: required for life and reproductive functions; men have ~2–5%, women have ~10–13%.

• Storage fat: subcutaneous and visceral fat; excess leads to overweight/obesity.

• Healthy ranges: Men: 8–19%, Women: 21–33%.

• Excess or insufficient fat affects health; very low body fat can be harmful.

Measuring Body Fat Percentage

1. U.S. Navy Method

• Measure waist, neck (both sexes), and hips (women only) circumferences.

• Use formulas (units in cm or inches):

For Males (Metric):

$$\text{BFP}=495\mathrm{/}(1.0324-0.19077\times {\log }_{10}(\text{waist}-\text{neck})+0.15456\times {\log }_{10}(\text{height}))-450$$

For Females (Metric):

$$\text{BFP} = 495 / \big(1.29579 – 0.35004 \times \log_{10}(\text{waist} + \text{hip} – \text{neck}) + 0.22100 \times \log_{10}(\text{height})\big) – 450$$

2. BMI Method (Estimate)

• Use BMI and age to estimate body fat.

Males:

$$\text{<span class="katex-html" aria-hidden="true"><span class="base"><span class="mord text"><span class="mord">BFP</span></span><span class="mrel">=</span></span><span class="base"><span class="mord">1.20</span><span class="mbin">×</span></span><span class="base"><span class="mord text"><span class="mord">BMI</span></span><span class="mbin">+</span></span><span class="base"><span class="mord">0.23</span><span class="mbin">×</span></span><span class="base"><span class="mord text"><span class="mord">Age</span></span><span class="mbin">−</span></span><span class="base"><span class="mord">16.2</span></span></span>}$$

Females:

$$\text{BFP=1.20×BMI+0.23×Age−5.4}$$

Fat Mass (FM) and Lean Mass (LM)

• Fat Mass = Body Fat % × Weight

• Lean Mass = Weight – Fat Mass

Health Considerations

• Excess body fat increases risks for heart disease, diabetes, stroke, and some cancers.

• Visceral fat (around organs) especially increases risk by altering hormones, cholesterol, and insulin sensitivity.

• Obesity classified as a major preventable cause of death by WHO.

• Body fat distribution and accumulation depend on genetics, lifestyle, gender, and age.

How To Use These in Your Calculator

• Ask users for required inputs (age, gender, height, weight, neck, waist, hip).

• Use unit conversions if needed (inches to cm, pounds to kg).

• Apply the U.S. Navy formula for primary body fat %.

• Calculate BMI and use it to estimate fat % by BMI method as secondary info.

• Display fat mass and lean mass based on weight and fat %.

• Compare the result with ACE categories to indicate fitness level.

• Show ideal body fat % based on age/gender using Jackson & Pollock data.