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Body Fat Calculator

Estimate your body fat percentage from simple tape measurements using the US Navy method.

Body Fat Calculator

Sex Measurement unit Height (inches) Neck circumference (inches) Waist circumference (inches)

Your result will appear here.

How to use

Select your sex and your measurement unit.
Measure with a soft tape, standing relaxed: neck just below the Adam's apple area, waist at the navel, and hip at the widest point (women's formula only).
Enter the numbers and click Calculate Body Fat.

What the number means

Body fat percentage is the share of your total weight estimated to be fat tissue rather than muscle, bone, water, and other lean tissue. The US Navy method estimates it from circumferences and height using a published formula — for men it uses height, neck, and waist; for women it adds hip. General adult ranges often described as athletic, fitness, average, and above average differ between men and women, because women naturally carry more essential fat.

Limits of the estimate

Tape measurements are sensitive to technique: a tape pulled tighter, measured after a meal, or placed a little higher or lower can shift the result by several percentage points. The formula was developed on specific groups and fits some body shapes better than others. It is a useful trend tool — same person, same tape, same spots, over time — but it is not as precise as laboratory methods, and small changes between two measurements may be measurement noise.

Healthy next steps

Focus on trends over months rather than a single reading, and pair the number with strength, stamina, sleep, and how you feel day to day. Gradual changes in movement and eating habits are more sustainable than chasing a specific percentage quickly. If a result worries you, a healthcare professional can discuss it in context and, if useful, arrange a more precise assessment.

Worked example: A man 70 inches tall with a 15-inch neck and a 34-inch waist: the US Navy formula gives about 17.5% body fat, in the general fitness range for men. A woman 65 inches tall with a 13-inch neck, 29-inch waist, and 38-inch hips would get about 27.3%.

Disclaimer: Results are estimates for general information only and are NOT medical advice. They do not diagnose or treat any condition. Talk to a healthcare professional before starting a diet, exercise program, or making health decisions based on these numbers.

Frequently Asked Questions

How accurate is the US Navy method?

It is a reasonable field estimate, typically within a few percentage points of laboratory methods, but tape placement and body shape affect accuracy. Use it for trends, not exact values.

Why does the women's formula need a hip measurement?

The published Navy formula for women includes hip circumference because fat distribution differs, and the extra measurement improves the estimate for women.

How do I measure my waist correctly?

Stand relaxed, breathe out normally, and measure at the navel with the tape snug but not compressing the skin. Do not hold your stomach in.

Does body fat percentage matter more than weight?

It adds useful context — two people at the same weight can differ greatly in fat and muscle — but neither number alone describes overall health or fitness.

How often should I re-measure?

Monthly is plenty. Body composition changes slowly, and frequent measuring mostly captures water shifts and tape variation.

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Body Fat Calculator