Body Fat Percentage Calculator

✦ Wellness with Emily · Free tool

Body Fat Percentage Calculator

Estimate body fat using the U.S. Navy tape-measure method, explore your body composition, and optionally save readings to compare over time — without treating a single number as a health verdict.

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Enter your measurements

All you need is a flexible tape measure. Measurements stay in your browser; nothing is submitted to this website.

Measurement formula

The original Navy equations use different body-measurement profiles for women and men. Choose the one whose measurement pattern is appropriate for you; this is not a statement about gender identity.

cm
kg
cm

For the female equation, measure your natural waist at its narrowest point.

cm

Just below the larynx, with the tape snug but not tight.

cm

Around the fullest part of the buttocks, tape level.

For adults only. This estimate is sensitive to where you place the tape. Take measurements standing, relaxed, after an ordinary exhale, without pulling in your stomach. Use the same approach when comparing later readings.

How this body fat calculator works

The Navy circumference method was developed as a quick population screening estimate for adults. It is convenient but not a substitute for clinical assessment.

What goes into the formula?

The male equation uses height, abdomen and neck. The female equation uses height, natural waist, hips and neck. We convert everything to inches before applying the base-10 logarithm equation.

Is it accurate?

No tape-measure equation can directly measure body fat. Measuring technique and individual body shape can affect accuracy. Consider multiple readings as rough estimates, not exact percentages.

Is fat-free mass all muscle?

No. Fat-free mass includes organs, body water, bones and muscle. If you enter your weight, we estimate fat and fat-free mass from the same approximate percentage — these are not independent measurements.

Does this determine whether I need to lose weight?

No. Body-fat estimates and BMI can offer context, but neither alone determines someone’s health or treatment needs. A clinician can interpret results alongside your history and other markers.

BMI Calculator ↗Understand your adult weight-for-height screening result. Waist-to-Height Ratio ↗Put your waist measurement into another useful context. TDEE & Calorie Calculator ↗Estimate energy needs, not body fat directly. Protein Calculator ↗Plan protein intake alongside strength training. What “Skinny Fat” Means ↗Why scale weight and body composition can differ. Cardio vs. Weights ↗Understand how different activities support health and fitness.

Important: This tool is intended for nonpregnant adults and is not suitable for children. The equations were developed in military populations and may be less accurate for different body types and populations. It does not diagnose obesity, determine a safe weight goal or replace professional medical care.

References: National Academies / NCBI: Body Composition in the Military Services · CDC: BMI and body composition context.