Diet Coke vs Diet Dr Pepper: Caffeine (46 vs 41 mg), Aspartame

Diet Coke lists 46 mg of caffeine per 12 fl oz can, and Diet Dr Pepper's product facts page gives approx. 41 mg per 12 fl oz can. Both are presented with aspartame as the listed sweetener, and both list 0 calories, 0 g sugars and 0 g carbohydrates per serving. Sodium differs, at 40 mg for Diet Coke and 60 mg for Diet Dr Pepper.

This guide sets those label facts side by side so you can weigh them yourself. Background: Diet Coke has been sold since 1982, according to Coca-Cola's own product page.

Key takeaways

• Diet Coke lists 46 mg of caffeine per 12 fl oz can. Diet Dr Pepper's product facts page gives approx. 41 mg per 12 fl oz can.
• The ingredient lists quoted from each brand's own page name aspartame as the only sweetener, with no acesulfame potassium, sucralose or stevia shown.
• Sodium is 40 mg per 12 fl oz Diet Coke can and 60 mg per 12 fl oz Diet Dr Pepper can, according to each brand's Nutrition Facts panel.
• Both cans list 0 calories, 0 g sugars and 0 g carbohydrates per 12 fl oz serving. Caffeine, sodium and ingredient wording differ between the two labels.

Diet Coke vs Diet Dr Pepper at a Glance: Same 12 fl oz Can, Different Label Lines

Both products are compared here per 12 fl oz can. Diet Coke's 12-pack UPC is 0049000028911 and its single can UPC is 049000006582. Diet Dr Pepper's 12-pack UPC is 0078000083163.

Label item (per 12 fl oz can)	Diet Coke	Diet Dr Pepper
Caffeine	46 mg (stated)	Approx. 41 mg (KDP wording: approx.)
Caffeine per fl oz (derived)	About 3.8 mg	About 3.4 mg
Sweetener in ingredient list	Aspartame only (no acesulfame potassium, sucralose or stevia listed)	Aspartame only (no acesulfame potassium, sucralose or stevia listed)
Sodium	40 mg (2% DV)	60 mg (3% DV)
Sodium source	Brand Nutrition Facts panel	Brand Nutrition Facts panel
Calories	0	0
Total sugars	0 g	0 g
Total carbohydrate	0 g	0 g
Preservative	Potassium benzoate	Sodium benzoate
Flavor wording	Natural flavors (specific substances not disclosed)	Natural and artificial flavors (specific substances not disclosed)
Phenylketonurics statement	Shown on product page	Not disclosed on KDP product facts page text

The table covers the items that differ or that each brand states directly. Everything else on the two ingredient lists is the same.

Footnote: Open Food Facts cross-checks for Diet Coke (0049000028911) agree with the brand figures above for ingredients, caffeine and sodium.

How Much Caffeine Is in Diet Coke vs Diet Dr Pepper per 12 oz Can?

Diet Coke has 46 mg and Diet Dr Pepper approx. 41 mg per 12 fl oz can. The 5 mg gap is roughly 12 percent more caffeine in Diet Coke. That 12 percent is arithmetic from the stated label values only, and the Diet Dr Pepper figure is approximate.

Per fluid ounce, the arithmetic works out to about 3.8 mg for Diet Coke and about 3.4 mg for Diet Dr Pepper. Those are derived figures, not separate label claims. Diet Dr Pepper's caffeine number is presented as approximate, so the exact amount in any given can was not disclosed.

The FDA has cited a common reference point for adults. In its FDA consumer update on caffeine, the agency says: 'For most adults, the FDA has cited 400 milligrams a day, that's about two to three 12-fluid-ounce cups of coffee, as an amount not generally associated with negative effects.' The same guidance notes there is 'wide variation in both how sensitive people are to the effects of caffeine and how fast they eliminate it from the body.'

As simple arithmetic only, 400 mg divided by 46 mg is about 8.7 cans of Diet Coke, and 400 mg divided by 41 mg is about 9.8 cans of Diet Dr Pepper. This is arithmetic only. It is not a per-can limit set by the FDA, and it is not a target or a recommendation.

The FDA advises that people who are 'pregnant, trying to become pregnant, or breastfeeding' talk with a health care provider about whether to limit caffeine, per the same consumer update. Caffeine from other foods and drinks adds to the total, and those sources are not part of this label comparison.

Which Sweeteners Are Listed on Diet Coke vs Diet Dr Pepper Labels?

The ingredient lists quoted from each brand's own page name aspartame as the only sweetener. Neither list quoted here shows acesulfame potassium, sucralose or stevia. Labels change over time, so check the sweetener line on the can in hand.

The FDA's aspartame and other sweeteners page states that 'aspartame is approved for use in food as a sweetener' and that it is 'about 200 times sweeter' than table sugar. The FDA ADI for aspartame is 50 mg/kg body weight per day. The milligrams of aspartame per can were not disclosed for either drink, so this comparison cannot rank the two cans by aspartame amount.

Sweetener combinations differ across other Coca-Cola and Dr Pepper products, so compare the exact product name on the can. For a side-by-side look at a related pairing, see Dr Pepper Zero vs Diet Dr Pepper: Aspartame, Ace-K and Caffeine.

How Does Sodium Compare in Diet Coke vs Diet Dr Pepper per Can?

Diet Coke lists 40 mg of sodium per 12 fl oz can, which is 2 percent of the Daily Value. Diet Dr Pepper lists 60 mg per 12 fl oz, which is 3 percent of the Daily Value. The Diet Dr Pepper can therefore lists 20 mg more sodium than the Diet Coke can.

An older Open Food Facts entry for Diet Dr Pepper lists 53 mg per 355 ml, which is a different label version. This comparison uses the 60 mg figure from the brand's own Nutrition Facts panel.

A few related products show other numbers. Caffeine-free Diet Coke lists 40 mg of sodium, and Diet Cherry Coke lists 30 mg. Sodium on the panel can also differ between flavors and pack formats, so the Nutrition Facts panel on the specific package in your hand is the reference to use.

What Is on the Full Ingredient List of Diet Coke vs Diet Dr Pepper?

Diet Coke's ingredient list reads: carbonated water, caramel color, aspartame, phosphoric acid, potassium benzoate (to protect taste), natural flavors, citric acid and caffeine. Diet Dr Pepper's list reads: carbonated water, caramel color, aspartame, phosphoric acid, natural and artificial flavors, sodium benzoate (preservative) and caffeine.

A quick label checklist shows where the two differ:

• Preservative: Diet Coke names potassium benzoate, described as there to protect taste. Diet Dr Pepper names sodium benzoate, described as a preservative.
• Acid: Diet Coke lists citric acid in addition to phosphoric acid. Diet Dr Pepper lists phosphoric acid only.
• Flavors: Diet Coke lists natural flavors. Diet Dr Pepper lists natural and artificial flavors.
• Caffeine: both list caffeine as an ingredient, with the caffeine amounts above.

The FDA's sodium benzoate regulation, 21 CFR 184.1733, says the ingredient 'is used in food at levels not to exceed good manufacturing practice' and that 'current usage results in a maximum level of 0.1 percent in food.' The amounts of potassium benzoate, sodium benzoate, citric acid or phosphoric acid in each can were not disclosed. The specific substances in 'natural flavors' and 'natural and artificial flavors' were also not disclosed.

Do Diet Coke and Diet Dr Pepper Both Carry Phenylalanine Warnings?

Diet Coke's product page shows the statement 'PHENYLKETONURICS: CONTAINS PHENYLALANINE'. The Diet Dr Pepper product facts page text does not show a comparable statement, so check the can directly.

Phenylalanine is an amino acid that is part of aspartame. The FDA explains that people with phenylketonuria (PKU), a rare genetic disorder, 'should avoid or restrict aspartame,' and that aspartame labels 'must include a statement to inform people with PKU that the product contains phenylalanine.' Anyone with PKU or a question about it should follow guidance from their own health care team and read the can directly.

Is Aspartame in Diet Coke and Diet Dr Pepper Regulated or Under Review?

Both cans list aspartame, which the FDA describes as approved for use in food as a sweetener.

The International Agency for Research on Cancer (IARC) placed aspartame in Group 2B, 'possibly carcinogenic' to humans, in 2023. The FDA disagrees with that conclusion. The FDA's statement reads: 'The FDA disagrees with IARC's conclusion that these studies support classifying aspartame as a possible carcinogen to humans.' IARC and JECFA issued their conclusions on July 14, 2023. According to the FDA, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) 'did not raise safety concerns for aspartame under the current levels of use and did not change the Acceptable Daily Intake (ADI).'

These label figures cannot establish how any individual will respond to aspartame or caffeine.

How Do Calories, Sugars and Carbohydrates Compare Between the Two Cans?

Both labels list 0 calories, 0 g total fat, 0 g total sugars, 0 g added sugars, 0 g total carbohydrate and 0 g protein per 12 fl oz serving. The Open Food Facts entries for both products also list 0 kcal.

The Keurig Dr Pepper page highlights the Diet Dr Pepper can as 'Sugar Free' and 'Diet or Low-Calorie', and lists it as 'Recyclable'. Those are brand descriptors, and the Nutrition Facts panel remains the reference for numbers.

For comparison with zero-sugar versions, Dr Pepper Zero Sugar is listed at approximately 41 mg of caffeine, with acesulfame potassium and sodium phosphate added, and 60 mg of sodium. To compare the two zero-sugar cans, see Dr Pepper Zero Sugar vs Coke Zero: Caffeine (41 vs 34 mg).

How Can Shoppers Check the Labels of Diet Coke and Diet Dr Pepper Themselves?

Labels can change, and pack formats differ, so it helps to check the package you are holding. A practical checklist:

• Confirm the pack size and UPC, since the 12-pack and single can have different codes.
• Read the serving size on the Nutrition Facts panel, which is 12 fl oz for both products discussed here.
• Compare the caffeine statement, and note whether it is given as an exact figure or an approximate one.
• Look for the sweetener names in the ingredient list, and confirm whether any sweetener is absent.
• Check for a phenylketonurics statement, which the Diet Coke page shows and the Diet Dr Pepper page text does not.
• Note the preservative and flavor wording, since the two lists differ on both.

Different flavors and versions, such as Caffeine Free Diet Coke or Diet Cherry Coke, can have different caffeine, sodium and sweetener lines, so compare the exact product name on the can.

Related Diet Soda Comparisons

For more side-by-side reading on sodas with similar label questions, see The 5 Sodas People Scan Most: Sweeteners, Acids and Colors and Coke Zero vs Diet Coke: Ingredients, Taste and Caffeine (34 vs 46 mg).

Read the can in your hand, and scan it with the Aurascan app to see each ingredient's explanation next to the Nutrition Facts panel.