Red Bull has more caffeine than brewed oolong tea on both counts: 80mg per 8.4 oz can against 37mg per 8 oz cup, and about 10mg per fluid ounce against 5. The serving sizes differ, so the table below shows both ways of counting.
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.
brewed oolong tea vs Red Bull: the numbers
| brewed oolong tea | Red Bull | |
|---|---|---|
| Caffeine per serving | 37mg per 8 oz cup | 80mg per 8.4 oz can |
| Caffeine per fl oz | 4.6mg | 9.5mg |
| Servings to reach 400mg (FDA context) | 10.8 | 5.0 |
Sources: brewed oolong tea's figure is verified in our brewed oolong tea caffeine guide against USDA FoodData Central (source); Red Bull's figure is verified in our Red Bull guide against Red Bull label / Caffeine Informer (source).
Which one should you pick?
Pick brewed oolong tea when you want the lighter dose or a slower ramp, and Red Bull 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
- brewed oolong tea: the full caffeine guide
- Red Bull: the full caffeine guide
- The verified caffeine database
- Every drink compared: the comparisons index
FAQ
Does brewed oolong tea or Red Bull have more caffeine? Red Bull: 80mg per 8.4 oz can versus 37mg per 8 oz cup for brewed oolong tea.
Which is stronger per ounce? Red Bull, at about 9.5mg per fluid ounce versus 4.6mg for brewed oolong tea.
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.