From smallest to biggest, penis sizes tend to be thought of as tiny, small, smallish, average, above average, big, very big, huge. Volume (length + girth) has a lot to do with penis size perception. For instance, a 6" length with 4.5" girth may be seen as smallish by most women. That same 6" length, but with 5.5" girth, may be seen as above average. Often questions and discussions stem around just length but it's volume that actually dictates size impression provided the length or girth aren't far outside the typical ranges. If the dick is very long or short then the volume perception becomes distorted and can separate to some degree. For instance, a 10" length with 4.5" girth is going to be seen as long and skinny. In that case the stark contrast between length and girth takes more of a hold on the visual than the volume does.