That all depends on the type of coffee you use, and how much you add. Cold brew coffee generally has a higher caffeine concentration than regular brewed coffee. On average, an 8-ounce (240 ml) cup of cold brew coffee can contain anywhere between 100-200 mg of caffeine. If you’re using store-bought cold brew, you can typically find more accurate measurements online. If you’re using homemade cold brew, regular brew, or espresso, it will all depend on the ratio of water to coffee grounds as well as the beans you use.