Translating from normie, sounds like 30-50g of beans, assuming a "cup" is 8 floz. and the water:coffee ratio is 15:1. Assuming Arabica, that's 450-750mg of caffeine.
I should heavily qualify this by saying that I don't think the study (which I have no access to) measured it this precisely or specifically. I think it was just people reporting roughly how many "cups" per day they drank over 40+ years. I guess I just get annoyed when I see "cups" as a unit of coffee science/health.
