What happens if you are transgender femal to male how do you figure out the size penis you would have if born a male?

Sizing up a man? : One common misconception about gender - how *we* identify ourselves - is that it is determined by our private parts or by our genetics. But that would mean that we'd consider a male soldier who lost his genitals in battle to then be "female"? | About your penis size question... Your closest biological male relatives' characteristics may serve as best basis for guessing.