NEWSFLASH: penis size does matter.
But (as you may be pleased to hear) bigger doesn't necessarily mean better.
The Authentic Women's Penis Size Preference Chart rates the length:girth ratio of the male member from "ideal" to "not satisfying". See below for more.
According to the chart, the ideal penis size is between 7.25-8.25inches in length and 6.25-6.5inches in circumference. Quite specific, but hey - us gals have needs.
Anything less than 5inches in length is deemed "not satisfying". The same can be said for penises with circumferences under 4.5inches or more than 7.5inches.