How much caffeine is there in a cup of coffee depends on how strong you make it. Generally, an 8oz cup of coffee contains about 95mg of caffeine. A cup of your regular instant coffee provides you with 6mg of caffeine – that is when you add 2 teaspoons of instant coffee crystals into 8oz of piping hot water. When you get a shot of espresso added to your coffee, you get another 65mg of caffeine from every ounce of espresso.