This suggests that there is only slightly more caffeine in a cup of coffee than in a single shot of espresso. A cup of coffee is approximately 4 ounces. A single shot of espresso is 1 ounce. So, if you were to compare a full cup of coffee at 4 ounces with 100 to 150 grams of caffeine to 4 ounces of espresso, then the 4 ounces of espresso should have between 320 to 480 miligrams of caffeine. Am I reading this correctly?