How much caffeine does coffee contain?

The caffeine content of coffee depends upon the variety of coffee as well as upon the method of brewing. Filter coffee generally contains more caffeine than espresso. The slow filter method allows the water to draw more caffeine out of the coffee powder than is possible in the espresso method, where the water is shot through the powder within seconds and under great pressure. According to coffee mix and method of preparation, the caffeine content of a cup of coffee fluctuates between 50 and 150 mg.