An average 8-ounce cup of coffee contains around 95 milligrams of caffeine, although this amount can vary depending on the type and amount of grounds used as well as the brewing process. The upper limit given for caffeine content in an 8-ounce cup of coffee is 200 milligrams.
When coffee beans are roasted prior to their use, caffeine can be removed from the beans. Darker roasts of coffee generally have less caffeine than lighter roasts. Using more grounds when brewing the coffee also increases the caffeine content. Espresso, which uses a brewing process that results in a fuller extraction from the grounds, has a higher caffeine content than coffee brewed with a different process.