It completely depends how many of these brownies you plan on eating in a sitting! From experience, it's hard to stop at just one. This information is completely estimated based on the average caffeine content of instant espresso and may vary depending on your brand: There will be about 150-200mg of caffeine in the entire batch of brownies. If you cut your brownies into 16 pieces like I did, that means each brownie will have 9-12mg of caffeine. This is similar to 1/4 cup regular brewed coffee.