Body Fat Calculator
Last updated: July 2026
Estimate body fat percentage using the U.S. Navy circumference method.
Estimated body fat
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- Estimated fat mass: —
- General category: —
On this page
Quick summary: Estimate body fat percentage using the U.S. Navy circumference method. Enter the requested values, calculate, review the result, and compare more than one realistic scenario before making a decision.
Read the complete guide
What this calculator does
The Body Fat Calculator estimates the percentage of body weight made up of fat using the measurements requested by the selected method. It can be useful for tracking broad changes over time when measurements are taken consistently.
How to use the calculator step by step
Enter the required body measurements carefully and use the same measurement technique each time. If circumference measurements are required, keep the tape level and snug without compressing the skin.
How the calculation works
Body-fat estimation formulas use relationships between body measurements and population body-composition data. Depending on the calculator, inputs may include height, waist, neck, hip measurements, weight, age, or sex.
Worked example and scenario testing
If an estimate changes from 24% to 22% over several months while measurements were taken under similar conditions, the trend may be more informative than either individual reading. Small day-to-day changes may simply reflect measurement variation.
How to interpret your result
The percentage is an estimate rather than a direct measurement of fat tissue. Different methods such as circumference formulas, skinfolds, bioelectrical impedance, DEXA, and hydrostatic weighing can produce different results.
Accuracy, assumptions, and limitations
Hydration, tape placement, body shape, recent exercise, food intake, and the population used to develop the equation can affect accuracy. The result should not be used alone to diagnose a health condition.
Common mistakes to avoid
Common mistakes include changing tape position between measurements, pulling the tape too tightly, mixing centimeters and inches, or treating a small single change as meaningful.
Privacy and browser-based calculations
Only measurement values are necessary. Avoid entering names, medical identifiers, photographs, or other unnecessary personal health data.