Free tool

Body fat calculator

Two field methods, two ways to measure: the U.S. Navy tape-measure method, which anyone can do at home, and Jackson-Pollock skinfolds, the protocol most gym body-composition assessments use. Both give you an estimate — not a lab measurement.

Tape measure

U.S. Navy method (tape measure)

Measure your neck just below the larynx, your waist at the navel (men) or at its narrowest point (women), and your hips at the widest point of the glutes. Snug tape, not tight — and don't suck in.

Estimated body fat

16.4%

Fat mass13.1 kg

Lean mass66.9 kg

Skinfolds

Jackson-Pollock skinfold method

Measure on the right side of the body with calipers, in millimetres. Take two or three readings per site and use the average. Results depend heavily on the measurer’s technique.

Estimated body fat

14.2%

Fat mass11.4 kg

Lean mass68.6 kg

Read this before trusting the number

Both formulas are regression equations built from specific groups of people. For an individual, error against reference methods is typically several percentage points — and it shifts with tape placement, the measurer's technique, and your build. Use one method, the same way every time, and compare the trend across weeks rather than a single value.

DEXA vs. calipers vs. BIA vs. photo: what each method gets wrong →Use your result in the FFMI calculator →

No tape, no calipers, no second person

Corpus estimates body fat from a guided photo check-in, captured the same way every week, and follows the trend alongside FFMI, weight, and muscle groups. It's still an estimate — but one you can repeat the same way on your own.

Download Corpus

Common questions

How do I calculate body fat percentage with a tape measure?

Use the U.S. Navy method: measure your height, neck, and waist (plus hips, for women) in centimetres and apply the Hodgdon and Beckett equation — the calculator above does the math. What matters most is measuring at exactly the same spots, with the same tape tension, every time.

How accurate is the U.S. Navy body fat method?

It was built as a practical screening tool, not a lab method. For a single person the estimate can be off by several percentage points, especially for people whose fat distribution differs from the original military samples. It is most useful for tracking change with a consistent measuring routine.

Which skinfold sites does the Jackson-Pollock method use?

The 3-site version uses chest, abdomen, and thigh for men, and triceps, suprailiac, and thigh for women. The 7-site version uses chest, midaxillary, triceps, subscapular, abdomen, suprailiac, and thigh for both sexes.

Why does my result differ from my smart scale?

Different methods make different assumptions. Smart scales use bioelectrical impedance, which shifts with hydration, meals, and recent exercise; tape and skinfold methods use equations based on external measurements. None of them is the "true" value — compare each method only against itself.

Can I estimate body fat without any equipment?

A tape measure is the minimum for the Navy method. The other equipment-free option is a photo-based estimate, which depends on taking photos under the same conditions each time.