Rockstar Original carries more total caffeine per serving (160mg per 16 oz can vs 160mg per 12 oz can), but ounce for ounce ZOA is actually the stronger drink at about 13mg per fluid ounce against 10. Which one "has more caffeine" depends on whether you measure the container or the concentration.
Rockstar Original vs ZOA: the numbers
| Rockstar Original | ZOA | |
|---|---|---|
| Caffeine per serving | 160mg per 16 oz can | 160mg per 12 oz can |
| Caffeine per fl oz | 10.0mg | 13.3mg |
| Servings to reach 400mg (FDA context) | 2.5 | 2.5 |
Sources: Rockstar Original's figure is verified in our Rockstar Original caffeine guide against Rockstar product page (source); ZOA's figure is verified in our ZOA guide against ZOA FAQ (source).
Which one should you pick?
Pick ZOA when you want the lighter dose or a slower ramp, and Rockstar Original 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
- Rockstar Original: the full caffeine guide
- ZOA: the full caffeine guide
- The verified caffeine database
- Every drink compared: the comparisons index
FAQ
Does Rockstar Original or ZOA have more caffeine? Rockstar Original: 160mg per 16 oz can versus 160mg per 12 oz can for ZOA.
Which is stronger per ounce? ZOA, at about 13.3mg per fluid ounce versus 10.0mg for Rockstar Original.
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.