When do you think it's safe to drive next day?

[CatsNotDogs]

Three large beers, one glass of prosecco 12.1 units in total. Started at 4pm finished at 10pm. Female weighing 10.6 stone.

Rough role of thumb is to allow an hour per unit, plus one hour on top of the total, counting from when you finished drinking.

Why would you count from when you finished drinking? Surely your body start to metabolise the alcohol from the first swallow. So I'd count down (up?) from when you start.

In the real world, no-one would even think about not driving the next day, and unless you're setting off before 6 am, you're unlikely to be still over the limit.

On Mumsnet, you wouldn't drive until a week on Monday, just to be safe.

By 6am you will be grand. A bit before probably.

I guess if you start counting from when you start drinking there's a chance you'll be counting units as metabolised before you even drank them, say if you had the first pint at 4, then a large gap before your next one. So it's safer and avoids that if you start at the finish time.