“Sorry, espresso fiends, if you’re looking for the most caffeine per fluid ounce at Starbucks, your best bet is a regular cup of coffee. A Starbucks double espresso has 150 milligrams of caffeine and a tall Starbucks Coffee has 260 milligrams of caffeine” No, that’s not how division works.
150 mg/2 oz of coffee: 75 mg per oz
260 mg/12 oz of coffee: ~22 mg per oz
Per drink the caffeine is higher in drip but not per ounce.