2 cups min to be alive
3rd cup to ease into serious work
I have 3 cups on though days, aim to do only 1 per day. I had a couple weeks without coffee, just tea and somedays nothing. I felt it was not worth it.
These days it's maybe 1-2 cups a day at breakfast.
Once upon a time I would have probably 8-10 cups a day and even a coffee every night at bedtime.