Starbucks Iced Coffee vs Diet Coke: which has more caffeine?

Starbucks Iced Coffee has more caffeine than Diet Coke on both counts: 165mg per 16 oz grande against 46mg per 12 oz can, and about 10mg per fluid ounce against 4. 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.

Starbucks Iced Coffee vs Diet Coke: the numbers

Sources: Starbucks Iced Coffee's figure is verified in our Starbucks Iced Coffee caffeine guide against Starbucks nutrition listing (source); Diet Coke's figure is verified in our Diet Coke guide against Caffeine Informer (source).

Which one should you pick?

Pick Diet Coke when you want the lighter dose or a slower ramp, and Starbucks Iced Coffee 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 Iced Coffee: the full caffeine guide
• Diet Coke: the full caffeine guide
• The verified caffeine database
• Every drink compared: the comparisons index
• Compare any two of 120+ drinks

FAQ

Does Starbucks Iced Coffee or Diet Coke have more caffeine? Starbucks Iced Coffee: 165mg per 16 oz grande versus 46mg per 12 oz can for Diet Coke.

Which is stronger per ounce? Starbucks Iced Coffee, at about 10.3mg per fluid ounce versus 3.8mg for Diet Coke.