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Health calculator

Body Fat Calculator

Estimate body fat percentage with circumference inputs. Measurement consistency matters more than false precision.

Circumference equations are estimates, not a direct body-composition measurement. Hydration, tape placement and posture can materially change the result.

How the estimate is calculated

The calculator uses circumference equations commonly associated with the U.S. Navy method. Inputs are converted to inches when metric values are entered.

Example

If you enter height 175 cm, neck 38 cm and waist 86 cm, the calculator estimates body fat from those circumference relationships rather than from weight alone. If the waist measurement changes to 84 cm using the same tape placement, the trend is more meaningful than a single exact percentage.

Common mistakes

Do not pull the tape tighter on later measurements, switch between relaxed and flexed posture, or compare this estimate directly with DEXA or skinfold results. Different methods can produce different percentages for the same person.

How to use the result

Treat the number as an estimate and focus on measurement consistency if you track change over time. This is not a medical assessment. DEXA, air displacement, hydrostatic weighing or clinician-guided methods may be more appropriate when body composition precision matters.

References

Last reviewed: 2026-05-17

Before relying on this result

Use this calculator together with the formula, assumptions, limitations and examples on the page. If the topic involves health, tax, lending, investment, legal, safety or current-rate decisions, treat the number as an estimate and check the relevant primary source or professional guidance.

Calculator metadata last reviewed: 2026-05-14.