Diet Coke vs Coca-Cola: caffeine compared
Diet Coke has 42 mg of caffeine per 11.2 oz can. Coca-Cola has 32 mg per 11.2 oz can.
Per serving Diet Coke is ahead: 42 mg against 32 mg, about 30% more. Per 100 ml Diet Coke is ahead: 12.8 mg against 9.7 mg, about 30% more.
| Diet Coke | Coca-Cola | |
|---|---|---|
| Serving | 11.2 oz can (330 ml) | 11.2 oz can (330 ml) |
| Caffeine per serving | 42 mg | 32 mg |
| Caffeine per 100 ml | 12.8 mg | 9.7 mg |
| Caffeine per fl oz | 3.8 mg | 2.9 mg |
| In the same 12 oz (355 ml) | 45 mg | 34 mg |
| Share of the 400 mg daily limit | 10% | 8% |
| Peak level, 45 minutes in | 38 mg | 29 mg |
| Time to fall below 40 mg | 45 minutes | already below |
| Latest for an 11 pm bedtime | 10:15 pm | any time |
| Servings to reach 400 mg | 9.5 | 12.5 |
What the numbers mean
Diet Coke has about a third more caffeine than regular Coca-Cola. It is a separate recipe, not Coca-Cola with the sugar removed, and the recipe calls for more caffeine.
Coke Zero, by contrast, matches regular Coca-Cola almost exactly. If you drink several cans a day and want less caffeine, moving from Diet Coke to Coke Zero cuts it by around a fifth without changing much else.
The full page for each
Common questions
Which has more caffeine, Diet Coke or Coca-Cola?
Diet Coke. One 11.2 oz can holds 42 mg, against 32 mg in one 11.2 oz can of Coca-Cola: about 30% more.
Which is the better choice late in the day?
Coca-Cola. One serving stays under 40 mg, so it can be had at any hour. For an 11 pm bedtime Diet Coke needs to be finished by 10:15 pm.
How many servings of Coca-Cola equal one Diet Coke?
About 1.3. One 11.2 oz can of Diet Coke holds 42 mg and one 11.2 oz can of Coca-Cola holds 32 mg.
How many can I have in a day?
Going by the 400 mg daily limit for healthy adults: about 9 servings of Diet Coke or 12 of Coca-Cola, if that is the only caffeine you have. Anything else with caffeine in it counts toward the same limit.
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Where these numbers come from
Every figure is calculated with the model the Cira app uses: caffeine peaks 45 minutes after you take it and halves every 5.7 hours, a typical value for healthy adults. The 40 mg sleep line is a working threshold of the model, and the 400 mg daily limit is the figure used by the European Food Safety Authority and the US FDA. These are averages. Smoking, pregnancy, the contraceptive pill and some medicines change how fast you clear caffeine. How the numbers are worked out.
