Caffeine in Green Tea According to the chart on this website, green tea has 15mg of caffeine for an 8 ounce cup. I didn't think it had any. And regular brewed tea has about 40mg on average. Drip coffee comes in at 115 to 175 mg. The site lists the amount of caffeine in all kinds of soft drinks in addition to tea and coffee.  ¶ 11:43 a.m.