How much caffeine is in a shot of espresso, compared to a cup of coffee?!

Question:

How much caffeine is in a shot of espresso, compared to a cup of coffee?

does a shot of espresso have more or less caffeine than a cup of brewed coffee? how much?

links would be great! i need to calculate safe levels of caffeine.
thanks

Additional Details

15 hours ago
"Espresso contains approximately twice the caffeine content per volume as regular brewed coffee, at approximately 40 milligrams per fluid ounce, but only about 1/3 the content per serving"

thanks yankeefan! i got that from your link...

15 hours ago
Red Ant-
thanks for that link! very helpful!

Answers: 15 hours ago
"Espresso contains approximately twice the caffeine content per volume as regular brewed coffee, at approximately 40 milligrams per fluid ounce, but only about 1/3 the content per serving"

thanks yankeefan! i got that from your link...15 hours ago
Red Ant-
thanks for that link! very helpful! I know that one shot of expresso has much more caffeine than a cup of coffee which is why they serve them in those tiny cups. hope this link helps.

http://en.wikipedia.org/wiki/espresso... I know that one shot of espresso has less caffeine than one cup of coffee (8 0z.) but I'm not sure exactly how many milligrams it contains. Here's a good caffeine chart. I found it doing Yahoo search. There are lots of them. http://www.cspinet.org/reports/caffeine....

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