Kirkland Energy Shot (Costco) vs Rockstar Original: which has more caffeine?

Kirkland Energy Shot (Costco) has more caffeine than Rockstar Original on both counts: 180mg per 2 oz shot against 160mg per 16 oz can, and about 90mg per fluid ounce against 10. The serving sizes differ, so the table below shows both ways of counting.

Kirkland Energy Shot (Costco) vs Rockstar Original: the numbers

Sources: Kirkland Energy Shot (Costco)'s figure is verified in our Kirkland Energy Shot (Costco) caffeine guide against Caffeine Informer (source); Rockstar Original's figure is verified in our Rockstar Original guide against Rockstar product page (source).

The concentration gap is the striking part: Kirkland Energy Shot (Costco) packs roughly 9 times the caffeine per ounce. Sipping speed matters at that density; a 2 oz shot finished in minutes hits differently than the same milligrams spread over a slow cup.

Which one should you pick?

Pick Rockstar Original when you want the lighter dose or a slower ramp, and Kirkland Energy Shot (Costco) 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

• Kirkland Energy Shot (Costco): 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

FAQ

Does Kirkland Energy Shot (Costco) or Rockstar Original have more caffeine? Kirkland Energy Shot (Costco): 180mg per 2 oz shot versus 160mg per 16 oz can for Rockstar Original.

Which is stronger per ounce? Kirkland Energy Shot (Costco), at about 90.0mg per fluid ounce versus 10.0mg for Rockstar Original.