The amount of caffeine in coffee varies widely depending on the type, brewing method, and serving size:

• Brewed coffee: A typical 8-ounce (about 240 ml) cup contains roughly 95 to 200 mg of caffeine, with an average around 150 mg. A 12-ounce cup can have between 113 to 247 mg of caffeine

• Espresso: A single 1- to 2-ounce shot usually contains about 63 to 127 mg of caffeine, with an average around 108 mg. A double shot can contain 200 to 300 mg

• Instant coffee: Generally contains less caffeine than brewed coffee, about 45 to 90 mg per 6 to 8-ounce cup

• Decaffeinated coffee: Not completely caffeine-free; typically contains 2 to 15 mg per 8-ounce cup, averaging around 3 to 7 mg

The caffeine content also depends on the coffee bean type, with robusta beans having roughly twice the caffeine of arabica beans

. In summary, a standard cup of brewed coffee usually contains approximately 95 to 200 mg of caffeine, but this can vary significantly based on preparation and coffee type.