How to correctly measure penis girth

[B_irish92]

Ive come across sites claiming different methods:

Average Penis Size Chart This one says thickest point (even if it's at the base)

How to Measure Your Penis Same...

Human penis size - Wikipedia, the free encyclopedia Wiki says it's a median or average girth

Plus I always thought you were supposed to measure from the middle of your penis

Now which is it?

 

[D_Crystallized Ginger]

It's nice to learn that the penis grow (slightly) even after 18 years... ending its growth around 30 years of age...

 

[Preakness]

Do both? It would cover the most discrepancies.
Some may be generally uniform, while others could vary a lot. Using only one may be potentially misleading.