Actual Penis Size
Self-reported values is scientific literature are notoriously unreliable, this fact may be most true when penis size is considered. In 2015, Hudson et al conducted a systematic review of penis size, where each study contained data from actual measurements. The results of more than 15,000 measurements, in several countries, revealed that the average flaccid length was 9.16 +/- 1.6 and the average erect length was 13.24 +/- 1.89 cm. Both the erect, measured as stretched length, and the flaccid results are shown below and also plotted with average vaginal linear length.
Perceived Penis Sizes
Using survey data first published here, researchers found that the perceived ideal penis size and the perceived average penis length were often different, with perceived ideal length always greater than perceived average. That is, the survey respondents, both male and female, suggested that ideal penis length is greater than the average length. These data are plotted below and also include the average penis length from Hudson et al.
Difference Between Actual and Ideal Penis Size
Of particular interest is the finding that both the perceived ideal and average are much larger than the average actual penis length. As shown below, both females and males desire an ideal penis that is larger than the average penis, by a few cm or just over an inch. In the case of females their ideal penis is 3.36 cm, or 1.32 in, larger than the average penis.