Coffee is the most common source of caffeine for adults. On average, one 8-ounce cup of coffee has about 95 milligrams of caffeine. Caffeine can boost alertness, improve focus, and even improve athletic performance when consumed in moderate amounts.
The amount of caffeine in coffee depends on the type, how it’s made, and even the brand. Here’s the average caffeine content of popular coffee drinks:
- Brewed coffee: 94.3 milligrams (mg) per 8-ounce serving, or 113–247 mg in a 12-ounce serving
- Espresso: 62.8 mg per 1-ounce shot
- Instant coffee: 62.4 mg per 8-ounce cup
- Cold brew: 153–238 mg per 12-ounce serving
- Decaf coffee: 2.4 mg per 8-ounce cup
As mentioned above, many factors can affect the amount of caffeine you get per cup, including:
- Degree of roast: Light roast coffees usually have more caffeine, while dark roasts often have bolder flavors.
- Type of coffee bean: There are many types of coffee beans. Robusta beans have about 1.4 times more caffeine than Arabica beans.
- Type of coffee: Espresso, cold brew, brewed coffee, instant coffee, and decaf have different amounts of caffeine.
- Origin: Conventional coffee beans may have more caffeine than organic coffee beans.
- Water temperature: Lower temperatures may reduce the amount of caffeine extracted from the coffee grounds.
- Coffee/water ratio: If you use more coffee grounds and less water, the drink will be stronger and have more caffeine per cup.
- Serving size: Larger servings, like 12- or 16-ounce coffee drinks, have more total caffeine than a standard 8-ounce cup.
- Brewing time: Contrary to popular belief, brewing time does not seem to have an effect on the total amount of caffeine in coffee.
Current guidelines recommend no more than 400 milligrams of caffeine per day for most healthy adults, which is about four 8-ounce cups of brewed coffee. Consuming too much caffeine can cause side effects like jitteriness, anxiety, trouble sleeping, or a fast heartbeat.
People who are pregnant should limit their intake to less than 200 milligrams per day, which is about one 12-ounce cup of coffee.
Serious side effects, including seizures, can happen with large doses (about 1,200 milligrams) of caffeine at once.
