The caffeine amount of coffee beans can vary depending on bean size and how darkly they were roasted.

This amount is the average caffeine content of an average size arabica bean which is the most common coffee bean used in making coffee.

When grinding coffee beans for use in making coffee, different brewing methods will have different caffeine extraction amounts.

Robusta Beans will have more caffeine than arabica beans and it is generally accepted that they contain double the caffeine of arabica beans.

Therefore each robusta bean could contain around 14mg of caffeine. However, Good quality robusta beans are difficult to find.

In general arabica coffee beans are 1.1% to 1.4% caffeine.