An 8-ounce cup of decaf coffee, whether brewed or instant, can contain 2 to 12 milligrams of caffeine. The actual caffeine content of the same amount of coffee varies because of several factors such as roast type, grind and brew time.
People with high blood pressure, arrhythmia and other medical conditions are advised to limit caffeine intake and in some cases avoid caffeine altogether. Drinking decaffeinated coffee is an option for those who want to reduce their caffeine intake. However, when people end up drinking more decaffeinated coffee than the amount of regular coffee they would have consumed, their caffeine intake is not necessarily lowered just because they switched to decaf.