What method does this calculator use?

The US Navy circumference method — a non-invasive estimate using neck, waist (and hips for women) measurements. It correlates well with DEXA scans within ±3–4%.

What is a healthy body fat percentage?

For men: 8–19% (athlete to acceptable). For women: 21–32%. Above 25% (men) or 32% (women) is classified as obese by ACE guidelines.

Is body fat % a better metric than BMI?

Yes for individuals with high muscle mass — BMI misclassifies muscular people as overweight. Body fat % directly measures fat, so it's more relevant for athletes, lifters and lean physiques.

🫀 Body Fat Calculator

Estimate your body fat percentage using the US Navy method (body measurements) or a BMI-based estimate. All calculations run in your browser — no data stored.

Sex

Unit System

Height (cm)

Neck circumference (cm)

Waist circumference (cm)

Hip circumference (cm) — women only

Age

Weight (kg) — for BMI method

About the Body Fat Calculator

The Body Fat Calculator uses two methods to estimate body fat percentage, giving you a more complete picture of your body composition than BMI alone. All calculations run entirely in your browser.

US Navy Method

Men: BF% = 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 36.76

Women: BF% = 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 78.387

Measurements must be in centimetres (or inches consistently). This method has an accuracy of approximately ±3–4%.

BMI-Based Estimation

Men: BF% = (1.20 × BMI) + (0.23 × Age) − 16.2

Women: BF% = (1.20 × BMI) + (0.23 × Age) − 5.4

This method requires only height, weight and age. It is less accurate than the Navy method and should be used as a rough guide only.

Body Fat Percentage Categories

Essential fat (men): 2–5% — the minimum needed for basic physiological function
Athletic (men): 6–13% | Athletic (women): 14–20%
Fitness (men): 14–17% | Fitness (women): 21–24%
Average (men): 18–24% | Average (women): 25–31%
Obese (men): 25%+ | Obese (women): 32%+

Why Body Fat Percentage Matters

Unlike BMI, body fat percentage directly measures the proportion of fat versus lean tissue (muscle, bone, organs). Two people with the same BMI can have very different health profiles — an athlete with high muscle mass and a sedentary person with high visceral fat may have identical BMIs but vastly different health risks. Tracking body fat over time is a more meaningful way to assess fitness progress.

How to Take Accurate Measurements

For the Navy Method, measure waist circumference at the navel (men) or narrowest point (women), neck circumference below the larynx, and (for women) hip circumference at the widest point. Use a flexible tape measure and take readings in the morning before eating for consistency.

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Important Note: This tool is intended to provide estimates and should not be used as a substitute for professional advice. Information generated by these calculators may be incomplete and does not account for all individual circumstances. Always seek the counsel of a certified expert (such as a financial advisor, healthcare provider, or licensed engineer) before taking action based on these results.

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