I've been trying to find the values of any sort of percentage composition of diet coke and I haven't found any luck other than one interviewee (Dr. MAUREEN STOREY [Senior Vice President, Science Policy, American Beverage Association]) who states

Soda is comprised mostly of water. A full-calorie soft drink has 90 percent water, and a diet soft drink is 99 percent water. Water is the most important nutrient that we have...

And that was all the information I have.

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    $\begingroup$ Is not energy content published on any drink bottle/can ? 1 g of sugar is equivalent to about 4.3 kcal, or about 4.2 times more kJ. // Referring cal as calorie ( "small calorie") and kcal=1000 cal as Calorie ( "big calorie" ) is very old and deprecated way to do so. Calorie itself is a deprecated, but tolerable unit among old school chemists. $\endgroup$
    – Poutnik
    May 20 at 9:19
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    $\begingroup$ Soda being 99 percent water is high questionable. Sweet sodas are at about 30% sugars by mass (!) Diet zero soda might approach that as for the CO2 content was calculated here in SE to be a few gram per liter soda. $\endgroup$
    – Alchimista
    May 20 at 13:18
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    $\begingroup$ I edited your question. One would not "boil a soda" to find it's caloric content. You might not understand what is meant by calorie content of a soft drink. The caloric content refers to the energy content (in kcal) of nutrients that a person can use to derive energy, for instance fat, carbs and even protein. Diet soda is diet soda because the sweeteners have a much higher sweetness than sugars such as sucrose or glucose. That means you hardly need sweetener, and therefore energy content is very low. $\endgroup$
    – Buck Thorn
    May 21 at 9:02
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    $\begingroup$ It is a pity the question is closed. Because the formula of Coca-Cola contains 16 ingredients. They are described in page 422 of the book by Mark Pendergrast, "For God, Country and Coca-Cola", Phoenix, London 1994. ISBN 1 85799 180 X. There is not enough room in this "Comment" to be more precise and give more details. $\endgroup$
    – Maurice
    May 21 at 9:24
  • $\begingroup$ @Maurice is the fact that the recipe is treated as industrial top secret a legend? $\endgroup$
    – Alchimista
    May 21 at 13:54

The major ingredient in Diet Coke is water (H$_2$O). The second ingredient is carbon dioxide (CO$_2$), about 30 psig, or three times atmospheric pressure. (I measured it with an automobile tire gauge.) Since CO$_2$ is soluble about 1.7 g/Kg at 20$^o$C at atmospheric pressure, Ref 1, this is about 5 g/L, or ~0.5%, using a density for Diet Coke of 1 g/L Ref 2.

enter image description here

So, in the list of ingredients for Diet Coke, Ref 3, everything will be between a maximum of 0.5%, down to about 0.01295% ("46 mg caffeine/12 fl oz" on the label of my 2L bottle).

And, as Matt Black noted, the recipe varies from country to country, and from time to time (and is noticeably different in cans vs fountain delivery, according to those with highly developed preferences), but the big impacts are provided by

#1. water

#2. carbon dioxide

#3. artificial sweetener

#4. caffeine and

#5. flavoring, which might include a little more acid, like citric or phosphoric.

Seltzer is just #1 plus #2; many caffeine-free beverages just leave out #4.

Ref 1. https://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html

Ref 2. http://web.physics.ucsb.edu/~lecturedemonstrations/Composer/Pages/36.34.html

Ref 3. https://www.coca-cola.ca/brands/diet-coke; see also https://www.huffpost.com/entry/coke-zero-sugar-taste-difference_n_597f71d7e4b00bb8ff3875d9 for varieties of Diet Coke


The major ingredients in diet coke vary by country but none are major components compared to sugar in full-fat drinks

The exact ingredient list of Diet Coke is not publically available but most of the flavourings are present in very low quantities. Also, the exact recipe varies over time and across countries (this is claimed to be an adaptation for local tastes). So it is hard to be exact

The major difference between a ~330 mL can of Diet Coke and normal (sugary) Coke is huge. Sugary Coke has about 40g of sugar for reference (other ingredients will be present in amounts similar to Diet Coke). The major components are:

  • sweetener (usually aspartame but others are sometimes mixed in at similar levels): ~100mg
  • caffeine: ~40mg
  • citric acid (or citrate): ~50mg
  • phosphoric acid (or phosphate): ~100mg

The total mass of water, for comparison, is about 330g (330,000mg) so there really isn't much of any of those key ingredients relative to the water.

This is very different to the sugary version of the drink where the sweetener is more than 10% of the total mass of the drink.

  • $\begingroup$ Full fat or sugar rich? $\endgroup$
    – Alchimista
    May 21 at 13:55
  • $\begingroup$ @Alchimista In normal, casual conversation "full fat" is a synonym for normal, sugary Coke. $\endgroup$
    – matt_black
    May 21 at 14:15
  • $\begingroup$ ah focus is on the side effects. Got it. $\endgroup$
    – Alchimista
    May 21 at 20:31

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