How much time does it really take for alcohol to leave your system?

I’m 21 and new to drinking. My friends like to go out to bars sometimes and I’d love to join them, but transportation is my concern. I would never want to drive intoxicated or even if I felt “sober” but had a BAC that is over the legal limit.

What’s the equation here for how many hours people of different body weights should wait between having a drink and driving? Surely there’s a spreadsheet for this somewhere lol.