Diet Pepsi contains 35 mg of caffeine per 12 oz can (355 ml / 12 oz). That is about 37% of the caffeine in a typical 8 oz cup of brewed coffee (about 95 mg). Concentration: 9.9 mg per 100 ml.
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Diet Pepsi Caffeine Content by Serving
Figures are for Diet Pepsi (PepsiCo).
| Serving | Volume | Caffeine | Per 100 ml | Level |
|---|---|---|---|---|
| 12 oz can | 355 ml / 12 oz | 35 mg | 9.9 mg | Low |
Source: caffeine figures from Caffeine Informer, accessed 2026-06-11. Values can vary by batch, location, and preparation; check the label or the source for the latest figures.
How Diet Pepsi Compares to Coffee
At 35 mg per 12 oz can, Diet Pepsi delivers about 37% of the caffeine in a typical 8 oz cup of brewed coffee (about 95 mg). For a wider comparison across drinks, try the caffeine comparison tool or browse the full caffeine database.
When to Stop Drinking Diet Pepsi Before Bed
A 12 oz can of Diet Pepsi (35 mg) stays under the 50 mg sleep-ready threshold from the first sip, so a normal serving is unlikely to delay sleep on its own. Multiple servings stack, though: caffeine's median half-life is about 5 hours, so a second or third serving in the afternoon can still add up past 50 mg by bedtime.
The Diet Pepsi sleep cutoff page has last-call times for four bedtimes, and the caffeine half-life calculator personalizes the curve to your metabolism.
