[bheadmaster]

> one cup has ~120mg of caffeine. This is 600 mg of caffeine. That's not a small dose

That's a fairly generous estimate, but that depends on which coffee you're drinking and how it's made. I usually make a cup of coffee by using at most a teaspoon of instant coffee powder, which contains ~50mg of caffeine. So 6 cups for me would be ~300mg of caffeine. That's a small dose when compared to my >1000mg caffeine pill habit in college, which caused the amphetamine-like burnout.

Though, it's good that you've brought this up - "a cup" is not a well-defined measurement of caffeine, and this elaboration resolves the ambiguity of my original post.

[Kirby64]

Instant coffee powder has extremely low caffeine vs. other brewing methods.

I'd suggest that most people, if they're drinking '5 cups a day' level, are brewing a pot of filter coffee via a drip machine. At that rate, each 'cup' (defined as 8 fl oz of coffee) should have something like ~100mg of caffeine.

If a 'cup' of coffee is something like a Starbucks Venti (20 fl oz), Starbucks claims it has somewhere between 410-475mg of caffeine. Two of those and you're approaching 1000mg of caffeine alone.