Starbucks London Fog carries more total caffeine per serving (40mg per 16 oz grande (40mg at every size) vs 34mg per 12 oz can), but ounce for ounce Big Red is actually the stronger drink at about 3mg per fluid ounce against 2. Which one "has more caffeine" depends on whether you measure the container or the concentration.
These are different categories of drink, which changes how the caffeine arrives. Energy drinks and sodas list an exact number because caffeine is a measured additive; brewed drinks vary with the beans and the brew, so their figures are compiled averages. The numbers here are the standard published values for each.
Big Red vs Starbucks London Fog: the numbers
| Big Red | Starbucks London Fog | |
|---|---|---|
| Caffeine per serving | 34mg per 12 oz can | 40mg per 16 oz grande (40mg at every size) |
| Caffeine per fl oz | 2.8mg | 2.5mg |
| Servings to reach 400mg (FDA context) | 11.8 | 10.0 |
Sources: Big Red's figure is verified in our Big Red caffeine guide against Caffeine Informer (source); Starbucks London Fog's figure is verified in our Starbucks London Fog guide against Starbucks nutrition listing (source).
Which one should you pick?
Pick Big Red when you want the lighter dose or a slower ramp, and Starbucks London Fog 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
- Big Red: the full caffeine guide
- Starbucks London Fog: the full caffeine guide
- The verified caffeine database
- Every drink compared: the comparisons index
FAQ
Does Big Red or Starbucks London Fog have more caffeine? Starbucks London Fog: 40mg per 16 oz grande (40mg at every size) versus 34mg per 12 oz can for Big Red.
Which is stronger per ounce? Big Red, at about 2.8mg per fluid ounce versus 2.5mg for Starbucks London Fog.
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.