Glossary

Definitions for key terms used in calculators and educational pages.

Key facts

Terms are educational and non-diagnostic.
Percentile and z-score are estimate-based outputs.
Country data is secondary and only used for erect length.
Global averages are the primary reference.

Average

A central reference value used for comparison.

Percentile

A rank showing where a value falls in a reference distribution.

Z-score

Distance from the average in standard deviation units.

Standard deviation

A statistical measure of how spread out values are around an average. In percentile estimates, it helps convert a measurement difference into a z-score.

Erect length

Length measured when erect, usually base to tip.

Erect girth

Girth means circumference around the shaft, not straight width. This matters for both average girth context and condom nominal-width estimates.

Girth

Girth means circumference around, not straight width. For condom sizing, it can be used to estimate nominal width.

Nominal width

The approximate flat width of a condom, usually measured in millimeters. It is related to circumference but is not the same as girth.

Flaccid length

Length measured when flaccid under consistent conditions.

Bone-pressed measurement

Length method pressing to pubic bone for consistency.

Non-bone-pressed measurement

Length method measured from skin-level base to tip.

Country average

Secondary erect length reference tied to country-level compiled data.

Global average

Primary educational reference based on pooled research.

Reference data

Published or compiled data used to build comparisons.

Educational estimate

A non-diagnostic statistical output for learning context.

Volume estimate

An approximate geometric calculation that combines length and girth. On this site, volume is estimated using a simplified cylinder model and should not be treated as a medical measurement.