Body Fat Calculator

How this body fat calculator works

The U.S. Navy method estimates body fat percentage from circumference measurements plus height. It is popular because it needs only a tape measure — no calipers or DEXA scan — and it produces a repeatable number if you measure the same sites the same way each time.

Measurements

Men typically use height, neck, and waist. Women use height, neck, waist, and hips. Place the tape level and snug but not compressing soft tissue. Waist is usually taken at the navel; neck below the larynx; hips at the widest point. Consistency beats perfection.

Worked example

A man who is 70 inches tall with a 16-inch neck and 34-inch waist will generally land in a moderate estimated body-fat range under the Navy equations. Increasing waist while holding other measures constant raises the estimate; reducing waist lowers it. That sensitivity is why the method is often used to track trends, not to obsess over a single decimal.

How to use it

1. Select sex so the correct equation and fields appear.
2. Enter height and the required circumferences in the units shown.
3. Record the estimate and optionally re-measure weekly under similar conditions.

Frequently asked questions

How accurate is the Navy method?

It is a circumference estimate with known error versus DEXA or hydrostatic weighing. Use it for trends under consistent measuring habits, not as a lab-grade reading.

When should I measure?

Same time of day, similar hydration, tape snug but not compressing soft tissue. Waist is usually measured at the navel level for this method — follow the field labels on the form.

Limitations

Circumference formulas have error versus lab methods. Hydration and posture affect tape readings. Estimate only; not medical advice.

Estimate only; not medical advice.