How much caffeine is in black tea?

Black tea may have 14 to 70 milligrams of caffeine per 8-ounce serving. However, decaffeinated black tea has 12 milligrams of caffeine or less per 8-ounce serving. The average amount of caffeine in an 8-ounce serving of black tea is 47 milligrams, according to the U.S. Department of Agriculture.

Different commercial brands of tea contain varying amounts of caffeine, and some brands offer decaffeinated versions of their black teas. The caffeine content depends on the length of time the tea is steeped in water. If the tea is steeped for a longer amount of time, the caffeine content in the resulting beverage is higher.