Although there is caffeine in green tea, it contains less caffeine than black tea, which has 60 - 90 mg caffeine, which is a lot less caffeine than coffee. So if you're looking to reduce your caffeine intake (but not eliminate it completely) green tea is a good choice. The average cup of coffee has about 100 - 250 mg of caffeine. The average cup of green tea has 35 - 70 mg of caffeine. You would need to drink at least three cups of green tea to get the same amount of caffeine as one cup of coffee.