An 8 ounce glass of iced tea has more caffeine (47 mg) than a 12 ounce serving of all of these drinks:

Diet Coke 45.6 mg
Dr. Pepper 41
Diet Dr. Pepper 41
Diet Sunkist Orange 41 (I was surprised it had any)
Pepsi 37.5
Diet Pepsi 36

I thought I was doing good just limiting myself to tea. I guess that would explain why I have not had any caffeine withdraw headaches yet.

Ounce for ounce iced tea does have about half the caffeine of coffee (80 – 175 mg), but you drink a lot more iced tea than you do coffee. A heavy coffee drinker might have three or four cups a day (4 cups x 8 ounces = 32 ounces) but I can drink almost an entire pitcher (96 ounces) of tea from our iced tea maker in a day, especially on the weekend when we are around the house more, and when it is hot outside.

I also recall hearing that the caffeine in tea is not chemically the same as the caffeine in coffee, and does not have quiet the same effect on a person.

Also we brew our tea with the ratio of one tea bag to 13.7 ounces of water, whereas when you brew a hot cup of tea you brew it stronger because you use considerably less water.

I guess once I am weaned off of coffee and Diet Coke I will pay attention to how much tea I drink.