C4 Ultimate Energy has more caffeine than Rockstar Original: 300mg vs 160mg in the same 16 oz can. That is a 140mg gap, and since the cans match, the per-serving number is the whole story.
C4 Ultimate Energy vs Rockstar Original: the numbers
| C4 Ultimate Energy | Rockstar Original | |
|---|---|---|
| Caffeine per serving | 300mg per 16 oz can | 160mg per 16 oz can |
| Caffeine per fl oz | 18.8mg | 10.0mg |
| Servings to reach 400mg (FDA context) | 1.3 | 2.5 |
Sources: C4 Ultimate Energy's figure is verified in our C4 Ultimate Energy caffeine guide against Caffeine Informer (source); Rockstar Original's figure is verified in our Rockstar Original guide against Rockstar product page (source).
Which one should you pick?
Pick Rockstar Original when you want the lighter dose or a slower ramp, and C4 Ultimate Energy 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
- C4 Ultimate Energy: the full caffeine guide
- Rockstar Original: the full caffeine guide
- The verified caffeine database
- Every drink compared: the comparisons index
- Compare any two of 120+ drinks
As an Amazon Associate, Barista Life earns from qualifying purchases.
Gear from this guide
FAQ
Does C4 Ultimate Energy or Rockstar Original have more caffeine? C4 Ultimate Energy: 300mg per 16 oz can versus 160mg per 16 oz can for Rockstar Original.
Which is stronger per ounce? C4 Ultimate Energy, at about 18.8mg per fluid ounce versus 10.0mg for Rockstar Original.
Barista Life runs on coffee people. Browse the Barista Life shop to support the site.
Get the good coffee stuff
One email a week: what we verified, what is worth buying, and what is not. No spam, unsubscribe any time.