In general, the average penis length is slightly longer in black or African American men compared to other ethnic or racial groups. The average length in this group is cm, but by comparison, the average white or Caucasian penis size is only a quarter of a centimeter smaller, at cm. Average penis length and girth by ethnicity/race - analysis of over 40 studies Dozens of studies into average penis size came up with varying results These studies were mostly conduced in the scientific fields of urology, virology and there are also a few commercial studies from condom manufacturers, from experiments in ED (erectile dysfunction. Mar 03, · What's the average penis size?The results are in, and they show it takes less to be well-endowed than you might think. The average length of an erect penis is inches ( centimeters) and the average circumference is inches ( centimeters), according to a new analysis of penis length studies involving more than .