Body fat calculator

What body fat percentage means

Body fat percentage is the proportion of your total weight that comes from fat tissue, as opposed to lean tissue (muscle, bone, organs, water). Two people of the same weight and height can have very different body compositions — which is why body fat percentage often gives a clearer picture of health than BMI alone.

Different levels of body fat serve different purposes. Essential fat (the minimum needed for healthy function) is around 2–5% for men and 10–13% for women. Athletic, fitness and acceptable ranges span above that. Carrying too little or too much body fat both carry health risks, so knowing where you fall helps you set informed goals.

US Navy method explained

The US Navy body fat formula is one of the most widely used circumference-based methods. It uses height and neck circumference for everyone, plus waist for men and waist plus hip for women. The formula estimates body density, then converts it to a body fat percentage using the Siri equation.

• For men: 86.01 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76
• For women: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387

The accuracy depends heavily on your measurements. Use a flexible tape measure, keep it level and snug against the skin, and measure at the narrowest point for the waist (just above the belly button) and the widest point for the hips. The neck is measured just below the larynx.

Healthy ranges by age and gender

• Men — Essential: 2–5% | Athletic: 6–13% | Fitness: 14–17% | Acceptable: 18–24% | Obese: 25%+
• Women — Essential: 10–13% | Athletic: 14–20% | Fitness: 21–24% | Acceptable: 25–31% | Obese: 32%+

These are general guidelines from the American Council on Exercise (ACE). Your age, genetics, activity level and personal health history all influence what is optimal for you. Body fat also tends to increase naturally with age, so do not compare yourself to elite athletes or fitness models.

Frequently asked questions

What is a healthy body fat percentage?

For men, 6–24% is generally healthy depending on age; for women, 14–31%. Athletic ranges (6–13% men, 14–20% women) are sustainable for active individuals.

How accurate is this calculator?

The US Navy method has a margin of error of about 2–4% compared to DEXA scans. Accuracy depends on taking measurements correctly.

What is the US Navy method?

It uses circumference measurements (neck, waist, hips for women) and height to estimate body density, then converts it to body fat percentage using well-established equations.

How do I measure my waist correctly?

Measure around your bare abdomen at the narrowest point, typically just above your belly button. Keep the tape snug but not tight, and parallel to the floor.

This tool is for information only and is not medical advice. Consult a health professional for accurate body composition assessment.