Body Fat Calculator
Estimate body fat percentage with the U.S. Navy Method using inches or centimeters, pounds or kilograms, and male/female category ranges.
Body Measurements
Goal Setting (Optional)
Enter your measurements
to calculate your body fat percentage
How to Measure
- Neck: Measure just below the Adam’s apple at the narrowest point.
- Waist: Measure around navel height with the tape level.
- Hips: Measure the widest point of the hips and buttocks.
What is the Body Fat Calculator?
The Body Fat Calculator estimates your body fat percentage with the U.S. Navy Method using height plus neck, waist, and hip measurements.
Because BMI uses only height and weight, muscular people can be misclassified. Body fat percentage is still an estimate, but it gives a clearer picture of body composition than scale weight alone.
When to use it
Use this page when you want a quick body composition estimate between professional measurements or before planning a fat-loss phase.
- Check your current body fat category from simple tape measurements.
- Compare how waist or hip changes affect the estimate.
- Review fat mass and lean body mass alongside the percentage.
- Set a target body fat percentage and preview a rough goal weight.
- Track weekly trends under the same measurement conditions.
Key features
The calculator keeps the essential inputs on one screen and updates the result as soon as the required measurements are available.
- Imperial or metric input, with imperial selected by default for U.S. users.
- Separate formulas for male and female body fat estimates.
- Automatic body fat category highlighting on the range scale.
- Fat mass and lean body mass estimates for easier interpretation.
- Optional target body fat planning with a rough goal weight.
How to use it
Choose the unit system that matches your measurements, enter the required values, and review the percentage, category, and goal summary.
- Select Male or Female.
- Keep Imperial or switch to Metric if your tape and scale use centimeters and kilograms.
- Enter height, weight, neck, waist, and hips if the female formula applies.
- Optionally add a target body fat percentage to see an estimated goal weight.
Details and interpretation
The U.S. Navy Method uses logarithmic formulas. For men it uses waist minus neck plus height, while the female formula uses waist plus hips minus neck plus height.
- Male formula: 86.010 × log₁₀(waist − neck) − 70.041 × log₁₀(height) + 30.30
- Female formula: 163.205 × log₁₀(waist + hip − neck) − 97.684 × log₁₀(height) − 104.912
For consistent results, measure in the morning, after the bathroom, before a large meal or workout, and keep the tape snug without pulling it tight.
Healthy ranges differ by sex because essential fat requirements are different. Very low values can affect hormones, recovery, immunity, and overall wellbeing.
Treat the result as a trend tool rather than a diagnosis. If you need clinical accuracy, confirm it with DEXA or a validated professional body-composition test.
Frequently Asked Questions
What is the difference between body fat percentage and BMI?
BMI estimates weight status from height and weight only, while body fat percentage estimates how much of your body weight is actually fat. That makes body fat percentage more useful for tracking body composition changes.
What is a healthy body fat percentage?
Healthy ranges vary by sex, age, and training status. As a broad guide, many adults aim for about 10–20% for men and 18–28% for women, while athletes may be lower.
How accurate is the U.S. Navy Method?
It is a practical field estimate, not a laboratory test. The result is often close enough for trend tracking, but measurement error and tape placement can shift the number by several points.
What are fat mass and lean body mass?
Fat mass is the portion of your weight that comes from fat tissue. Lean body mass is everything else, including muscle, bone, organs, and body water.
Can the result change during the day?
Yes. Food, hydration, bloating, training, and posture can all change circumference measurements. Compare results only when you measure under similar conditions each time.
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