Starbucks bottled Frappuccino (Mocha) has more caffeine than Diet Pepsi on both counts: 105mg per 13.7 oz bottle against 35mg per 12 oz can, and about 8mg per fluid ounce against 3. The serving sizes differ, so the table below shows both ways of counting.
These are different categories of drink, which changes how the caffeine arrives. Energy drinks and sodas list an exact number because caffeine is a measured additive; brewed drinks vary with the beans and the brew, so their figures are compiled averages. The numbers here are the standard published values for each.
Diet Pepsi vs Starbucks bottled Frappuccino (Mocha): the numbers
| Diet Pepsi | Starbucks bottled Frappuccino (Mocha) | |
|---|---|---|
| Caffeine per serving | 35mg per 12 oz can | 105mg per 13.7 oz bottle |
| Caffeine per fl oz | 2.9mg | 7.7mg |
| Servings to reach 400mg (FDA context) | 11.4 | 3.8 |
Sources: Diet Pepsi's figure is verified in our Diet Pepsi caffeine guide against Caffeine Informer (source); Starbucks bottled Frappuccino (Mocha)'s figure is verified in our Starbucks bottled Frappuccino (Mocha) guide against PepsiCo product facts (source).
Which one should you pick?
Pick Diet Pepsi when you want the lighter dose or a slower ramp, and Starbucks bottled Frappuccino (Mocha) when you actually need the bigger hit and know your tolerance. If you are stacking either with other caffeinated drinks through the day, run the math against the 400mg reference rather than guessing.
For context, the FDA cites 400mg of caffeine a day as an amount generally not associated with negative effects in healthy adults. Tolerance and health vary, so treat these numbers as information, not advice.
Related reading
- Diet Pepsi: the full caffeine guide
- Starbucks bottled Frappuccino (Mocha): the full caffeine guide
- The verified caffeine database
FAQ
Does Diet Pepsi or Starbucks bottled Frappuccino (Mocha) have more caffeine? Starbucks bottled Frappuccino (Mocha): 105mg per 13.7 oz bottle versus 35mg per 12 oz can for Diet Pepsi.
Which is stronger per ounce? Starbucks bottled Frappuccino (Mocha), at about 7.7mg per fluid ounce versus 2.9mg for Diet Pepsi.
Comparing caffeine? The caffeine comparison tool puts hundreds of drinks side by side, and the caffeine curfew calculator can check your cutoff time for tonight.