theteadetective.com › faq › which-tea-has-the-least-caffeineWhich Tea Has The Least Caffeine? - The Tea Detective Green tea has a lower amount of caffeine than black tea does, around 35 mg per 8-ounce (230 ml) cup, whereas a serving of black tea can have anywhere from 39-109 mg of caffeine ( 2, 8, 9 ). Which Teas are Highest in Caffeine? 5 High Caffeine Green Teas to Replace Coffee Watch on Which green tea is lowest in caffeine?