The amount of caffeine in one cup of coffee varies depending on the type of coffee, brewing method, and cup size. On average:

• An 8-ounce (about 237 ml) cup of brewed coffee contains approximately 80 to 100 milligrams (mg) of caffeine

• A 12-ounce cup can contain roughly 113 to 247 mg of caffeine, with an average around 150 mg

• Espresso, which is more concentrated, contains about 63 to 127 mg of caffeine per 1 to 2-ounce shot, but since servings are smaller, total caffeine per serving is often less than a large brewed coffee

• Instant coffee typically has less caffeine, around 45 to 80 mg per 6 to 8-ounce cup

• Decaffeinated coffee is not caffeine-free and usually contains about 2 to 5 mg per 8-ounce cup

Factors such as coffee bean variety, roast level, grind size, and brewing time also influence caffeine content, so these numbers can vary somewhat

. In summary, a standard cup of brewed coffee generally contains about 80–100 mg of caffeine. Larger cups or stronger brews will have more caffeine, while instant and decaf coffees have less