https://www.youtube.com/watch?v=q6Ygmg_haE0
In the video she talks about her method for categorising penis length with her hands. It's hard to know whether she's referring to bone pressed or not, so lets assume non-bone pressed. Figures included are based on average female hand width.
Entire erection covered by one hand (<2.91") = Small
Handful plus some (>2.91" - <5.82") = Average
Two hands (5.82") = Big
More than two hands (>5.82") = Porno big
Of course if her hands are bigger, like, up to the size of the average male hand width:
Entire erection covered by one hand (<3.3") = Small
Handful plus some (>3.3" - <6.6") = Average
Two hands (6.6") = Big
More than two hands (>6.6") = Porno big
She also says in the video she often prefers average penises because there's less effort required for sex and she doesn't have to worry about pain, discomfort, etc. Thought it was an interesting take from one of the most experienced female adult entertainment stars in the industry.
I know this is on length, but can be helpful in some other posters vivid imagination.