You do not specify if you refer to flacid-state or erect-sate.
In my opinion, for me, a penis is big according to this:
Flacid-state: a penis that is 15 cm - long in forward (without ceiling or measure top limit).
Erect-state: a penis that is 20 cm - long (without ceiling or top measure).
According to the sexólogos, an erect-penis is big if it is 18 cm - long or more.
The sexólogos use frequently this table of classification of erect-penis (it does not apply to flacid-size, Ok?).
01.- Micro-penis: From 1 cm-long to 5 cm-long.
02.- Small penis: From 6 cm-long to 11 cm-long.
03.- Average penis (standard penis or normal penis): From 12 cm-long to 17 cm-long.
04.- Big penis: From 18 cm-long to 25 cm-long.
05.- Enormous penis: From 26 cm-long in forward (without limit or top measure).
I say again: this one table of classification of sizes of penises (sizes in length, not perimeter) is applied ONLY for penises in erection; it is not applied for penises in soft-state.
Bye!.
At what size is concidered a large penis??