Warning: There's currently no reliable or recommended source of information about these averages.
A page for measuring the volume of balls I guess. This is not a very organized page, take every result with a grain of salt. All measurements should be of one single testicle, not both of them. For the "Rundle and Sylvester, 1962" study, it is advised to use this website instead as it provides percentages based on age as well.
NOTE: The website defaults to
centimeters as a measurement unit.