How many cups of coffee do Americans drink each day?

How to get close to this number

Multiply three numbers you can estimate. Take the adult population, apply the share who drink coffee on a given day — the explanation puts it around two thirds — and multiply by the average number of cups those people have. The result is in the hundreds of millions, and each of the three inputs is something you can reason about.

The pitfall is averaging across everyone. Coffee consumption is bimodal: a large group drinks none at all and a committed group drinks several cups daily. An average taken over the whole population describes nobody, and it will mislead you about both the total and the behaviour. Splitting into drinkers and non-drinkers before averaging is the correct move.

The claim in the explanation that coffee overtook tap water in these surveys deserves a caveat: it reflects what respondents report consuming on a given day in a survey about beverages, not total fluid intake. Survey-based consumption figures measure reported behaviour, which is systematically different from measured behaviour — usually in flattering directions.