Pure Leaf black iced tea has more caffeine than Starbucks London Fog on both counts: 54mg per 18.5 oz bottle against 40mg per 16 oz grande (40mg at every size), and about 3mg per fluid ounce against 2. The serving sizes differ, so the table below shows both ways of counting.
Starbucks London Fog vs Pure Leaf black iced tea: the numbers
| Starbucks London Fog | Pure Leaf black iced tea | |
|---|---|---|
| Caffeine per serving | 40mg per 16 oz grande (40mg at every size) | 54mg per 18.5 oz bottle |
| Caffeine per fl oz | 2.5mg | 2.9mg |
| Servings to reach 400mg (FDA context) | 10.0 | 7.4 |
Sources: Starbucks London Fog's figure is verified in our Starbucks London Fog caffeine guide against Starbucks nutrition listing (source); Pure Leaf black iced tea's figure is verified in our Pure Leaf black iced tea guide against PepsiCo label data (source).
Which one should you pick?
Pick Starbucks London Fog when you want the lighter dose or a slower ramp, and Pure Leaf black iced tea 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
- Starbucks London Fog: the full caffeine guide
- Pure Leaf black iced tea: the full caffeine guide
- The verified caffeine database
FAQ
Does Starbucks London Fog or Pure Leaf black iced tea have more caffeine? Pure Leaf black iced tea: 54mg per 18.5 oz bottle versus 40mg per 16 oz grande (40mg at every size) for Starbucks London Fog.
Which is stronger per ounce? Pure Leaf black iced tea, at about 2.9mg 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.