A 12 fl oz can of Pepsi has 38mg of caffeine, and Pepsi Zero Sugar has the same 38mg. Diet Pepsi runs a touch lower at 35mg. Those are the numbers straight off PepsiCo's official product facts site, not a guess. If you were expecting Pepsi Zero Sugar to be the loaded one, it used to be, and that changed.
Why Pepsi Zero Sugar isn't the caffeine bomb it used to be
For years the move was simple: if you wanted the most caffeine per Pepsi can, you grabbed the black-can zero sugar version. It carried roughly 69mg per 12 oz, close to double a regular Pepsi. That's why energy-drink-adjacent forum posts still quote it that way.
PepsiCo reformulated Pepsi Zero Sugar in the United States in early 2023 and dropped the caffeine down to match regular Pepsi. So the current US formula sits at 38mg per 12 oz, same as the classic blue can. If you are reading an older chart that says 69mg, it is out of date for the US market. Other regions, like Canada, still run higher, which is where a lot of the confusion comes from.
Practical version for behind the bar: regular Pepsi and Pepsi Zero Sugar are now interchangeable on caffeine. Diet Pepsi is the low one of the three. None of them are close to a cup of drip coffee, which typically lands around 95mg for 8 oz.
One thing worth knowing if you pull soda from a fountain instead of a can. Fountain caffeine can drift a little depending on how the machine mixes syrup and carbonated water, so a fountain Pepsi is not guaranteed to hit exactly 38mg for a given 12 oz pour. The canned and bottled numbers are the ones the label stands behind, so those are what we cite. Treat fountain as close enough rather than exact.
Pepsi caffeine by product and size
All figures below are for the US formulas as listed on PepsiCo's site. The 20 oz bottle numbers are scaled from the verified 12 oz per-ounce rate, since a bottle is just a bigger pour of the same drink.
| Product | Serving | Caffeine |
|---|---|---|
| Pepsi | 12 fl oz can | 38mg |
| Pepsi Zero Sugar | 12 fl oz can | 38mg |
| Diet Pepsi | 12 fl oz can | 34mg |
| Pepsi | 20 fl oz bottle (approx) | ~63mg |
| Pepsi Zero Sugar | 20 fl oz bottle (approx) | ~63mg |
The 12 oz figures come from pepsicoproductfacts.com. The 20 oz numbers are the same drink scaled up (about 3.2mg per fl oz), so treat them as close estimates rather than a printed label figure. For an independent cross-check, Caffeine Informer lists Pepsi at 38mg and Pepsi Zero Sugar at 38mg per 12 oz as well.
For context, the FDA cites 400mg of caffeine a day as an amount generally not associated with negative effects in healthy adults. How caffeine affects you depends on your own tolerance and health, so treat these numbers as information, not advice.
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How Pepsi stacks up against other sodas
Pepsi's 38mg puts it a few milligrams above Coca-Cola, which sits at 34mg for the same 12 oz can. Both are in the same low tier. Dr Pepper is a bit higher at 42mg. Mountain Dew, also a PepsiCo drink, is the outlier of the family at 54mg per 12 oz, so if someone hands you a Dew instead of a Pepsi they are getting noticeably more. The takeaway across regular cola is that they all cluster in the 30s and 40s, and the format that actually changes your intake is size, not brand. A 20 oz bottle of any of them carries more caffeine than a 12 oz can simply because there is more liquid in it.
If you want the full rundown on how these compare and where the real caffeine lives, these go deeper:
- How much caffeine is in Coca-Cola
- How much caffeine is in Dr Pepper
- The full Barista Life caffeine database
FAQ
Does Pepsi Zero Sugar have more caffeine than regular Pepsi? Not anymore in the US. Both are 38mg per 12 oz after PepsiCo reformulated Pepsi Zero Sugar in 2023. The old formula was around 69mg, which is where the "more caffeine" reputation came from.
Which Pepsi has the least caffeine? Of the three main colas, Diet Pepsi is lowest at 35mg per 12 oz. If you want none at all, Caffeine Free Pepsi and Caffeine Free Diet Pepsi exist for that reason.
Is 38mg of caffeine a lot? No. A 12 oz Pepsi has less than half the caffeine of a standard 8 oz cup of drip coffee, which runs around 95mg. It is well under the FDA's 400mg per day reference point on its own.