Here's what the maximum amount of caffeine you should be drinking in a day looks like

It turns out that while a can of the vilified energy drink has 80 milligrams of caffeine (just one-fifth the maximum amount you should have each day, according to the Mayo Clinic), one small cup of Starbucks drip coffee has more than three times that amount.

Regardless of how you get your caffeine, it's important to keep in mind that it's a stimulant with some positive and negative effects.

And the amount of caffeine that's in various drinks - or even the same drink from a different chain - can vary dramatically. Here's how much caffeine is in everything from a can of Coke to a plain coffee from McDonald's: