What Is a Healthy Body Fat Percentage? (By Age & Sex)
Automated technical check: . Scope and review policy
A body-fat percentage describes estimated fat mass as a proportion of total mass. It is not, by itself, a verdict on health. The Body Fat Calculator uses tape measurements in a circumference equation; it does not measure fat directly or establish a universal healthy target.
The equation actually used here
All measurements are converted to centimeters. For the male variant, estimated density D = 1.0324 - 0.19077 x log10(waist - neck) + 0.15456 x log10(height). For the female variant, D = 1.29579 - 0.35004 x log10(waist + hips - neck) + 0.221 x log10(height). The displayed percentage comes from 495 / D - 450.
These are the density equations implemented by DigiCalc. Other online tools may use a different direct-percentage equation, a different unit system or measurement procedures. Similar names do not mean the equations and results are interchangeable.
Worked example and input limits
Using the male variant with height 178 cm, neck 38 cm and waist 85 cm gives 16.4% after rounding. The logarithm uses waist minus neck, or 47 cm here. A waist of 38 cm with a neck of 38 cm produces a zero difference and cannot be evaluated in that equation.
Nonpositive or nonfinite measurements, unsupported formula sex, invalid logarithms, or results outside the physical interval above 0% and below 100% show no estimate. The calculator no longer silently clamps implausible measurements to a plausible-looking low or high percentage. Decimal display precision does not imply measurement accuracy.
Reference bands are not a diagnosis
The displayed bands are broad informational labels. They do not account for age, medical history or a measurement method's individual error. An output in an athlete or fitness band does not prove fitness; an output outside a band does not establish a diagnosis. This guide does not prescribe a body-fat target or give a universal accuracy margin for tape estimates.
Do not use it as an official Navy assessment
The U.S. Navy publishes its own body-composition assessment guide, procedures and tables. This continuous equation does not reproduce the official 2026 process or certify eligibility. For an official assessment, use the current applicable service guidance and assessors.
For comparisons, use consistent units, tape locations and technique. Differences between this estimate, a scale estimate and a clinical assessment may reflect different methods rather than a real short-term body-composition change. Adult BMI is another screening calculation with its own limitations; neither tool replaces an individual health assessment.
Sources and Scope
Technical example checks are not independent professional review. Sources were checked for the statements above on October 6, 2026.