How much caffeine in tea？

As a standard, a 235 ml (equivalent to an ordinary glass of boiling water) cup of green tea contains 30-50 mg of caffeine, a 235 ml cup of black tea contains about 47 mg of caffeine, the caffeine content of 235 mg of instant coffee is :62 mg, and the caffeine content of freshly ground coffee is :95 mg.

The amount of caffeine in coffee and tea depends on a number of factors. Generally speaking, the higher the temperature of the water, the more caffeine is released from the coffee beans and tea leaves, so espresso made under steam pressure has a higher caffeine content than coffee made under atmospheric pressure; the caffeine content and the time of brewing the tea are also related, usually, the longer the brewing time, the higher the caffeine content.

The caffeine content is also related to the brewing time, usually the longer the brewing time, the higher the caffeine content. The variety of tea, the origin of the tea, or the part of the tea that is harvested also has an important effect on the caffeine content. The darker the roasted coffee beans, the lower the caffeine content. For tea, the caffeine content of the tea tree's pointed tip leaves is much higher than that of the larger leaves below. Oolong, green, black and white teas all contain caffeine.