How accurate is the tape method?

Within a few percent for most people — great for tracking trends. DEXA scans are the gold standard for a one-off precise reading.

What formula does the Body Fat Calculator use?

It calculates using US Navy: %BF (men) = 495 / (1.0324 − 0.19077·log10(waist−neck) + 0.15456·log10(height)) − 450. The guide above walks through what each part means with a worked example.

How accurate is the Body Fat Calculator?

It uses established, widely-accepted formulas and gives a reliable estimate for the values you enter. Everyone's body is different, so use the result as a helpful guide — not a medical diagnosis.

Is the Body Fat Calculator a substitute for medical advice?

No. It's an educational estimate. For guidance tailored to you, always consult a qualified healthcare professional before making changes.

Is this calculator free to use?

Yes — every GKCalculators calculator is 100% free with no sign-up required. Create a free account only if you want to save your calculation history across devices.

All calculations run instantly in your browser. Nothing is sent anywhere unless you tap ‘Explain my results’ (AI) or ‘Save’ while signed in.

Can I share my result?

Yes. Tap Share and we copy a link with your exact inputs baked in, so anyone who opens it sees the same result.

Body Fat Calculator

Estimate body-fat percentage with the U.S. Navy tape method.

Compare

Gender

Height (cm)

Neck (cm)

Waist (cm)

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Estimated body fat

16.4%

Category: Fitness (U.S. Navy method)

AI Breakdown & Smart Takeaway

Plain-English insight on your numbers

Get a personalized explanation of what these results mean — and how to improve them.

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How the Body Fat Calculator works

This Body Fat Calculator uses the U.S. Navy tape method to estimate your body fat percentage from simple circumference measurements, making it accessible to anyone without specialized equipment. It's designed for adults who want a reliable, research-backed snapshot of their body composition to guide fitness and health decisions.

The US Navy tape method estimates body-fat percentage from a few circumference measurements — no calipers needed.

We map your result to fitness categories from essential fat to obese, by gender.

Formula

US Navy: %BF (men) = 495 / (1.0324 − 0.19077·log10(waist−neck) + 0.15456·log10(height)) − 450

Pro tips

Measure first thing in the morning for consistency.

Key terms

Body Fat Percentage: — The proportion of your total body mass that is composed of fat tissue, expressed as a percentage.
U.S. Navy Method: — A circumference-based body fat estimation technique developed by the U.S. Navy that uses neck, waist, hip (women only), and height measurements in a logarithmic regression formula.
Body Composition: — The breakdown of the human body into its component parts — primarily fat mass and fat-free (lean) mass — used to assess health and fitness beyond simple body weight.
Lean Body Mass: — The total weight of everything in your body except fat, including muscle, bone, organs, and water.
Essential Fat: — The minimum amount of body fat necessary for basic physiological function, approximately 2-5% for men and 10-13% for women.
Circumference Measurement: — A tape-measure reading of the distance around a specific body site, used in the Navy method as a proxy for regional fat distribution.