While that science is helpful for creating the simplest cuppa Joe ever, these processes have an adverse effect on both flavor and caffeine content. For example, your average cup of instant coffee usually contains anywhere between 30 and 90 milligrams of caffeine, whereas a standard cup of regular coffee might boast somewhere between 70 and 140 milligrams. Of course, too much caffeine is unhealthy, so do what you want with this information.