How i measure the penis from pubic bone or pelvic bone wich one is true measurement?

See answer: True penile length is measured by holding the flaccid penis on manual stretch and measuring (on the upper or topside of the penis) the distance from the tip of the penis back to the pubic bone at the very base of the penis. While results vary slightly across reputable studies, the consensus is that the mean human penis is approximately 12.9–15 cm (5.1–5.9 in) in length.

Pubic bone: Push down on skin over pubic bone next to ; touchin side of penis. Pull on flaccid penis ; measure to tip of glans will give accurate stretched flaccid length. Similar with erect penis for erect length.