1 shot of espresso has pretty much the same amount of caffeine a 1 6 oz cup of coffee. Regular drip coffee used to have more caffeine back in the days when all the major coffee producers (Folgers, Cain, etc) used Robusta. Robusta has twice the caffeine as arabica. Espresso is typically made with mostly arabica beans. However, nowdays arabica is so cheap all the major coffee producers use 100% arabica in most of their products. Many espresso blends have started using up to 10-15% robusta beans, so the trend is reversing.