Bling Fling Posted:

E-Peen length = total base value / highest base value * 13

When we find the base values for newly acquired E-Peen, we can extrapolate to find the values of older, now unattainable Peen and come up with a comprehensive list on the wiki.

They said the first 6 inches would be much easier to gain, so I doubt the equation is linear like that. There’s probably diminishing returns, where your length approaches 13 as the sum of your peens’ base values approaches infinity.