I don't know it. This link contains doctors' studies and has a chart that includes flaccid to erect amongst it's measurements.
Blackwell Synergy - Cookie Absent
On that chart notice that the 200 Turkish men had a combined averaged flaccid of 2.7" and upon erection 5.0". The largest flaccid on the chart is homosexual men at 4.1" and their overall erect size at 6.5".
Here, from the lines in which there is a flaccid to erect comparison I'll put it all in order from shortest flaccid to longest flaccid:
Flaccid-----------------------------------Erect
2.7"--------------------------------------5.0"
3.4"--------------------------------------5.7"
3.5"--------------------------------------5.1"
3.6"--------------------------------------5.6"
3.8"--------------------------------------6.1"
3.9"--------------------------------------6.1"
4.1"--------------------------------------6.5"
At another site, Thundersplace, overall the 3" flaccids averaged out to 5.75" erect (grew 2.75") and the 5" flaccids averaged out to 7.25" erect (grew 2.25"). Thundersplace's penis size chart closely matches doctor studies, so it stands to reason that it's flaccid to erect database can pretty much be trusted to be accurate enough to trust the flaccid to erect correlation .
And at another site that contains photos along with the measurements:
http://www.erectionphotos.com/softH...dGalleryP01.htm
Flaccid Length--------Averaged Erect Length----------------Amount of increase in inches
1.00-1.49---------------------4.71-------------------------------------+3.50
1.5-1.99----------------------4.89-------------------------------------+3.14
2.00-2.49---------------------4.88-------------------------------------+2.63
2.50-2.99---------------------4.92-------------------------------------+2.17
3.00-3.49---------------------6.07-------------------------------------+2.82
3.50-3.99---------------------6.08-------------------------------------+2.33
4.00-4.49---------------------6.69-------------------------------------+2.44
4.50-4.99---------------------7.00-------------------------------------+2.25
5.00-5.49---------------------7.35-------------------------------------+2.10
5.50-5.99---------------------7.80-------------------------------------+2.05
6.00-6.49---------------------na----------------------------------------na
6.50-6.99---------------------9.00-------------------------------------+2.25
Generally speaking it does mean something. Not that my posts will change any minds. Of course it won't. Why is that?
So, in general, upon erection, do growers become as big as showers? No.
Upon erection do growers tend to close the gap some. Yes, but not all that much.