Pepsi Zero Sugar has more caffeine than Diet Coke: 69mg vs 46mg in the same 12 oz can. That is a 23mg gap, and since the cans match, the per-serving number is the whole story.
Pepsi Zero Sugar vs Diet Coke: the numbers
| Pepsi Zero Sugar | Diet Coke | |
|---|---|---|
| Caffeine per serving | 69mg per 12 oz can | 46mg per 12 oz can |
| Caffeine per fl oz | 5.8mg | 3.8mg |
| Servings to reach 400mg (FDA context) | 5.8 | 8.7 |
Sources: Pepsi Zero Sugar's figure is verified in our Pepsi Zero Sugar caffeine guide against PepsiCo product facts (source); Diet Coke's figure is verified in our Diet Coke guide against Caffeine Informer (source).
Which one should you pick?
Pick Diet Coke when you want the lighter dose or a slower ramp, and Pepsi Zero Sugar 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
- Pepsi Zero Sugar: the full caffeine guide
- Diet Coke: the full caffeine guide
- The verified caffeine database
- Every drink compared: the comparisons index
- Compare any two of 120+ drinks
FAQ
Does Pepsi Zero Sugar or Diet Coke have more caffeine? Pepsi Zero Sugar: 69mg per 12 oz can versus 46mg per 12 oz can for Diet Coke.
Which is stronger per ounce? Pepsi Zero Sugar, at about 5.8mg per fluid ounce versus 3.8mg for Diet Coke.
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