The amount of caffeine in coffee depends on what type of bean we used, and how these beans are roasted and prepared. The big question we always notice is which has more caffeine in espresso, or coffee. An ounce of espresso contains 63 mg of caffeine whereas a regular coffee contains between 12 to 16 mg of caffeine per ounce. So the amount of caffeine depends on the volume of coffee you take in your cup.