Is this body fat index calculator medically accurate?

No. The tool uses the US Navy body fat formula based on circumference measurements. It can give a rough estimate but does not replace medical exams or professional diagnosis.

Does muscle mass affect the body fat estimate?

Yes. The formula cannot see how much of your weight is muscle versus fat. Very muscular people often receive a higher estimated body fat than their real value.

How often should I measure my body fat index?

For tracking trends, many people re-measure every 2–4 weeks at a similar time of day and under similar conditions. Day-to-day changes are normal, so focus on the long-term trend.

● Body fat estimate in seconds

Body fat index calculator

Calculator

This is an estimate only. It does not replace medical advice.

Gender

Unit system

Age

Height ft / in

Feet

Inches

Height cm

Body weight kg

Neck circumference cm

Waist at navel cm

For educational use only. Always talk to a health professional for personal advice.

How to measure

For consistent results, use a flexible tape measure, take your time and repeat each measurement at least once. Small changes in how you place the tape can shift the result.

Neck and waist

Neck: Stand tall, look straight ahead and relax your shoulders. Measure just below the Adam’s apple at the narrowest point.
Waist at navel: Stand relaxed, do not suck in your stomach. Measure horizontally around the abdomen at belly button level.
Keep the tape level and snug, but not cutting into the skin.

Try to measure at the same time of day if you want to compare results over time.

Hips, height and weight

Hips (women): With feet together, measure around the widest part of the hips and glutes.
Height: Measure barefoot, standing straight against a wall, heels touching the floor.
Weight: Use a stable scale on a hard surface, ideally in the morning with minimal clothing.

This calculator only estimates body fat index from circumference data. It cannot see your fitness level, muscle mass or medical history.

FAQ

Is this calculator medically accurate?

No. It uses the US Navy body fat formula, which is based on simple tape measurements. It can give a rough estimate but does not replace a scan, medical exam or professional diagnosis.

Does muscle mass change the result?

Yes. The formula cannot see how much of your weight is muscle versus fat. Very muscular people often get a higher estimated body fat than their real value.

How often should I measure?

Many people re-measure every 2–4 weeks, at a similar time of day under similar conditions. Day-to-day fluctuations are normal, so the long-term trend is more important.