It found that the average caffeine level in the cups of tea (black English style teas) was 40mg vs 105mg in the average cup of drip coffee. The amount of caffeine in coffee or tea depends on a number of factors, including the method and length of brewing or steeping.
Caffeine in coffee vs black tea
As a rule of thumb, coffee has about twice as much caffeine as tea. Caffeine levels vary a lot, though, in both beverages. More specifically a cup of: coffee has between 95 and 200 milligrams of caffeine. black tea has between 14 and 70 milligrams of caffeine. green tea has between 24 and 45 milligrams of caffeine.