Surprisingly, the strength of the taste of coffee has nothing to do with the amount of caffeine it contains. Rather, caffeine content depends on the type of coffee, the degree of roast and the ratio of coffee to water used during the brewing process.

Facts about coffee and caffeine:

• Caffeine content of a 5 fluid oz. cup of regular coffee ranges from 60 mg to 180 mg, depending on the type and the roast of coffee.
• Caffeine content of 1 % fluid oz. of espresso ranges from 90 mg to 120 mg, also depending on the type of coffee used and the style of roast.
• Caffeine content does change by degree of the roast. The lighter roasts contain more caffeine than the darker roasts.

Caffeine varies between species of coffee trees. Arabica coffees contain about 1% caffeine by weight in green form, while robusta beans contain about 2% by weight.