Driving after drinking moderately; or, how do you know where .08 is?

[CanKid]

i drink and drive, but i dont drunk and drive

[Ulysses]

Godfather,

"I'm mostly curious about how you guys make the call for yourselves as to whether you are able to drive or not."

Something like this: A couple of drinks, I am fine to drive. Have a few more, I am not fine to drive. Have a few more, then I am fine to drive again.

This is why I don't drive at all when I'm going to drink.