Hi Tanya, thanks for this interesting question.
Many people are concerned about their health, and the impact of caffeine intake in their lives. So, hopefully, my answer will help you, and many others too.
You’ll be surprised to learn that a double espresso has almost the same amount of caffeine as a cup of drip coffee. According to most research, many variables complicate to offer a single number. According to the Department of Nutrition of the United States, a double shot of espresso has around 126 mg of caffeine. In comparison, an 8 oz cup of coffee (near 240 ml) has 95 to 128 mg of caffeine.
Explaining the reasons behind it is interesting. So, please, stay with me. I promise all this information is relevant to answer your question.
First, let’s consider the size of each serving. A double shot of espresso measures approximately 60 ml, while a regular cup of coffee can measure 250 ml and even more. That’s more than four times the size of a double espresso!
The tricky thing here is the concentration of each beverage. As you may know, espresso is more concentrated than drip coffee. While an espresso takes 1 to 2 water per part of coffee, drip coffee can use 14 to 18 parts of water per part of coffee. For this reason, a regular cup of coffee can rival the caffeine content with a double shot of espresso.
The ratio of coffee and water is what we call the brew ratio, and I’m sure you can find more information about it in an article in The Coffee Lab. Getting back to my point, to serve a cup of drip coffee of 250 ml, we use near 18 grams of ground coffee, a similar amount to a double espresso dose.
Other variables change the caffeine content in each beverage. Water temperature, grind size, and pressure change extraction. Additionally, Robusta coffee beans have around twice the caffeine content of Arabica coffee beans, so there are plenty of factors that can change caffeine content in your favorite coffee.