The wang size also seems to somehow depend on the race. Survey of more than 1000 Indian men showed that about 60% of Indian men have penīses which are between 3 and 5 cm shorter than international standards used in c0nd0m manufacture. Some of the studies also show that Asian men have penīses shorter by 1 inch (2.5cm) comparable to Caucasian males.
Anyway, if you want to do some check yourself, you can use the following chart (printable):
There are also many myths surrounding relation of penīs and some other parts of the body such as finger of shoe size. For instance I've found this chart:
Yet, it does not seem to be anyhow accurate thus I consider this as a myth.