One shot of Starbucks espresso contains approximately 75 milligrams of caffeine

. This is based on Starbucks' standard single shot size of about 0.75 ounces. For context:

• A Tall size drink usually has one shot (75 mg caffeine).
• Grande and Venti sizes typically have two shots (150 mg caffeine).
• Blonde espresso shots have slightly more caffeine, around 85 mg per shot

Thus, a single Starbucks espresso shot delivers a concentrated caffeine dose of about 75 mg.