Diet Pepsi has more caffeine than Sprite: 35mg vs 0mg in the same 12 oz can. That is a 35mg gap, and since the cans match, the per-serving number is the whole story.
Diet Pepsi vs Sprite: the numbers
| Diet Pepsi | Sprite | |
|---|---|---|
| Caffeine per serving | 35mg per 12 oz can | 0mg per 12 oz can |
| Caffeine per fl oz | 2.9mg | 0.0mg |
| Servings to reach 400mg (FDA context) | 11.4 | n/a (caffeine-free) |
Sources: Diet Pepsi's figure is verified in our Diet Pepsi caffeine guide against Caffeine Informer (source); Sprite's figure is verified in our Sprite guide against Caffeine Informer (source).
The concentration gap is the striking part: Diet Pepsi packs roughly 292 times the caffeine per ounce. Sipping speed matters at that density; a 12 oz can finished in minutes hits differently than the same milligrams spread over a slow cup.
Which one should you pick?
Pick Sprite when you want the lighter dose or a slower ramp, and Diet Pepsi 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
FAQ
Does Diet Pepsi or Sprite have more caffeine? Diet Pepsi: 35mg per 12 oz can versus 0mg per 12 oz can for Sprite.
Which is stronger per ounce? Diet Pepsi, at about 2.9mg per fluid ounce versus 0.0mg for Sprite.
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