Question: how much caffeine is in a diet soda?
Answer: How much caffeine is in Coke? How much caffeine is in Diet Coke? People are often surprised when they learn that the amount of caffeine in Coke or Diet Coke is much less than in the same-sized coffee. Coke's caffeine content is 34mg for a 12-oz can, and Diet Coke caffeine content is 46mg.