Your measurements
Your measurements stay in this browser. Results are informational estimates, not medical advice.
How to use the body fat calculator
Measure consistently and treat the result as an estimate.
Choose units and sex
Select the unit system and sex used by the published equation.
Measure circumference
Enter height, neck and waist; female calculations also use hip circumference.
Review the estimate
Use the percentage as a tracking estimate, not a direct body-composition measurement.
Frequently Asked Questions
How does this body fat calculator work?
It uses the US Navy circumference method to estimate body-fat percentage. The equation combines height with neck and waist measurements for men, and height with neck, waist and hip measurements for women.
Where should I measure my waist, neck and hips?
Keep the tape measure level, snug and against bare skin without pulling it tight. Measure your neck just below the larynx, your waist at the narrowest point or around the navel if that is your consistent landmark, and your hips at their widest point. Use the same locations every time.
Why does the calculator ask for sex?
The published US Navy equations use different measurement combinations and constants for male and female bodies. Select the option that matches the equation you want to use; it is an equation input rather than a judgement about your identity or health.
How accurate is the US Navy body fat method?
It provides a practical estimate, not a direct measurement. Results can differ from methods such as DEXA, hydrostatic weighing or skinfold testing, and tape placement, posture and normal changes in hydration can affect the estimate. It is generally more useful for monitoring a personal trend than treating one result as exact.
When is the best time to take body measurements?
For consistent comparisons, measure at a similar time of day, ideally before eating or exercising, using the same tape and landmarks. Avoid comparing a single reading with one taken after a large meal, hard workout or major change in hydration.
Why did my estimated body fat percentage change even though my weight did not?
The estimate is based on circumferences as well as height, so small differences in tape placement, posture, bloating and hydration can change it. Compare several measurements taken consistently and focus on the longer-term pattern.
Can I use this calculator to diagnose my health or set a target?
No. This calculator is for general information and progress tracking, not diagnosis or personalised treatment. Body-fat percentage is only one health measure; speak with a qualified clinician if you need advice tailored to a medical condition, pregnancy, eating concerns or athletic performance.
Should I use metric or imperial measurements?
Either is fine. Choose the unit system you can measure most accurately and enter every measurement in the unit shown by the calculator. In imperial mode, enter height and circumferences as total inches.