At least if you believe [link|http://groups.google.com/groups?&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&selm=3moscq%24dg7%40newsbf02.news.aol.com&rnum=1|this]:

3.1.5. How much caffeine does tea have in it? Does green tea have more or
less caffeine than black tea?

The amount of caffeine in a cup of tea varies with the variety of tea and
the brewing time. Here are some rough figures, with comparisons to coffee
and other caffeine sources, from *All the Tea in China* by Kit Chow and
Ione Kramer (China Books, 1990):

Black tea infused for 5 minutes: 40-100 milligrams caffeine per 5-oz. cup
Black tea infused for 3 minutes: 20-40 milligrams
Oolong tea: 12-55 milligrams
Green tea: 8-36 milligrams

Coffee, drip: 60-180 milligrams
Coffee, instant: 30-120 milligrams
Coffee, decaffeinated: 2-5 milligrams
Coca-Cola (TM), 12-oz serving: 46 milligrams

As you can see from this chart, green tea has relatively little caffeine,
but it still has some. Mild green tea may have about as much caffeine as
some decaffeinated coffees.


I vaguely recall some other Usenet discussion on caffeine that claimed that the concentration in tea *decreased* with steeping time. It never made sense to me.

In graduate school my recipe for tea was to boil some clean water, steep a tea bag (e.g. Red Rose) in a 12 oz glass mug for 20 - 30 minutes, remove the bag, add about 2 teaspoons of sugar, and enjoy (yum!). (I've never been a fan of milk in tea.) I'd have about 4 of those a day, then wondered why I had trouble sleeping at night...

I rarely drink tea now because I get evil caffeine withdrawal headaches. :-(

Cheers,
Scott.
(Who agrees that nothing is simple. :-)