The majority of all caffeine consumed worldwide comes from coffee—in some countries, this figure is as high as 85%.
Depending on the type of coffee and method of preparation, the caffeine content of a single serving can vary greatly. On average, the following amounts of caffeine can be expected in a single cup of coffee—about 207 milliliters (7 fluid ounces)—or single shot of espresso—about 44–59 mL (1.5–2 fl oz)
Drip coffee: 115–175 mg
Espresso: 100 mg
Brewed: 80–135 mg
Instant: 65–100 mg
Decaf, brewed: 3–4 mg
Decaf, instant: 2–3 mg
Taken from www.coffeefacts.com
