The legal limit in the United States for added caffeine in drinks is 6mg/ounce or 72mg to a can of soda.
Coke has 45mg per 12oz, Mountain Dew 55mg, and Jolt Cola maxes out the legal limit with 72mg per can. Since coffee is naturally caffeinated, it is not regulated for caffeine content. 12oz of coffee has around 120-350(!)mg of caffeine in it, depending on how it’s brewed.
I’m paraphrasing an article from the Nation, who I’d consider a credible source. It jives with research I did a while back when I wanted to know how much caffeine was in Red Bull (80mg per 12oz, but it comes in ~8oz cans).
One NoDoz tablet has 200mg of caffeine.