Free fitness calculator
Body Fat Calculator
Estimate your body fat percentage with the US Navy circumference method, then see your estimated lean body mass and fat mass.
For information only: This calculator gives an estimate, not a medical diagnosis or substitute for professional advice.
Enter your measurements
Use a flexible tape measure and enter each measurement in inches.
Your estimate
Based on the measurements you entered.
- Estimated lean body mass
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- Estimated fat mass
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This is an estimate, not a diagnosis. Small measurement differences can affect the result.
Simple steps
How to use the body fat calculator
- Select the formula. Choose male or female to show the matching US Navy equation and required measurements.
- Measure carefully. Enter height, weight, waist, and neck in the units shown. Female formula users also enter hip circumference.
- Calculate your estimate. Select “Calculate body fat” to see your estimated percentage, general category, lean mass, and fat mass without leaving the page.
Calculation method
The US Navy body fat formula
The US Navy method estimates body fat from height and circumference measurements. All measurements in these equations are in inches, and log10 means the base-10 logarithm.
Male formula
86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76
Female formula
163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387
Estimated fat mass is your weight multiplied by the estimated body-fat fraction. Estimated lean body mass is your weight minus estimated fat mass. Results are rounded for display only.
Know the limits
Limitations and health disclaimer
This circumference-based method is a screening estimate, not a direct body-composition measurement or medical diagnosis. It does not account for every factor that can affect body composition, such as age, ethnicity, pregnancy, fluid shifts, or how fat and muscle are distributed.
The general labels use simplified adult reference bands. For men, the cutoffs are below 2%, 2–5.9%, 6–13.9%, 14–17.9%, 18–24.9%, and 25% or higher; for women, they are below 10%, 10–13.9%, 14–20.9%, 21–24.9%, 25–31.9%, and 32% or higher. These correspond to below reference, essential fat, athlete, fitness, average, and higher body fat categories. They are broad descriptions, not personalized health targets.
Even careful users can get different results because of tape position, tape tension, posture, breathing, or rounding. For better comparisons, measure at a similar time and under similar conditions. If you need a clinical assessment or have concerns about your health, speak with a qualified healthcare professional.
Common questions
Frequently asked questions
How accurate is the US Navy body fat calculator?
The US Navy circumference method provides an estimate, not a direct measurement. Tape placement, posture, breathing, and measurement technique can all change the result. Use consistent technique to follow trends, and consult a qualified health professional if you need a clinical assessment.
Where should I measure my waist, neck, and hips?
Measure your neck just below the larynx without compressing the tape. For men, measure the abdomen horizontally at the navel; for women, measure the waist at its narrowest point and hips at their widest point. Keep the tape level and snug, and take each measurement more than once.
Does the calculator need my age?
No. The Navy circumference equations shown here do not include age. Because body-fat norms can vary with age and other individual factors, the general category is only a broad description and is not an age-adjusted health assessment.
What are lean body mass and fat mass?
Lean body mass is your estimated weight excluding fat mass. Fat mass is your estimated weight attributable to body fat. Both values are calculated from the estimated body-fat percentage and the weight you enter, so they share the estimate’s limitations.