UK Coke Zero Sugar aims for a taste closer to original Coca-Cola, while Diet Coke has its own lighter flavour. Both are sugar-free, but their current ingredient lists differ.
The difference at a glance
Coke Zero Sugar aims for a taste closer to original Coca-Cola; Diet Coke uses a different flavour blend with a lighter taste. Both regular UK drinks are sugar-free and very low in calories. Their current ingredient lists are not identical, and neither regular version is caffeine-free. [1] [2] [3]
This guide compares the regular, caffeinated UK Coca-Cola Zero Sugar and Diet Coke descriptions checked on 6 October 2026. “Coke Zero” is common shorthand for Zero Sugar. Flavoured, caffeine-free and imported versions are separate products, so their labels should not be substituted into this table.
| Detail | Coca-Cola Zero Sugar | Diet Coke |
|---|---|---|
| Intended flavour | Closer to Coca-Cola Original Taste | A separate, lighter flavour blend |
| Sugar per 100 ml | 0 g | 0 g |
| Energy per 100 ml | 0.3 kcal / 1.3 kJ | 0.4 kcal / 1.6 kJ |
| Listed sweeteners | Aspartame, acesulfame-K and enzymatically produced steviol glycosides | Aspartame and acesulfame K |
| Acid / acidity-regulator entries | Phosphoric acid; sodium citrates | Phosphoric acid and citric acid |
| Caffeine in this version? | Yes: caffeine flavouring is listed | Yes: caffeine flavouring is listed |
| Phenylalanine warning | Contains a source of phenylalanine | Contains a source of phenylalanine |
The flavour distinction is the intended product positioning, not a finding from a taste test conducted for this article. The nutrition and ingredient rows describe the current UK regular product entries. Compare the pack in your hand if its formulation or market differs. [1] [2] [3]
If you want an alternative built around the familiar Original Taste profile, Zero Sugar is the relevant starting point. If you prefer the different, lighter Diet Coke profile, the “Zero” name does not make it an automatic upgrade. Preference is not something an ingredient table can decide for you.
A simple personal comparison is to serve small amounts at the same temperature in two similar glasses, without looking at the cans while tasting. Record which you prefer before checking the labels. That is a way to explore your own preference, not a claim that the drinks will be indistinguishable or that one wins for everyone.
The shared 0 g sugar figure answers one nutrition question. It does not reveal the complete flavour blend. Both drinks list aspartame and acesulfame K; the current regular Zero Sugar entry also lists enzymatically produced steviol glycosides. That ingredient difference should not be silently removed because an older comparison lists only two sweeteners. [2] [3]
An ingredient list still does not give you the amount of each sweetener or a complete recipe. It is enough to identify the listed difference; it is not enough to calculate a sweetness score or reconstruct the drink. The “natural flavourings” entry also leaves the blend unspecified.
The table uses a common denominator of 100 ml. For an illustrative 330 ml serving, multiply a per-100 ml value by 3.3. This calculation uses the published, rounded figures; it is not an independent measurement of the drink.
Zero Sugar: 0.3 kcal × 3.3 = 0.99 kcal.
Diet Coke: 0.4 kcal × 3.3 = 1.32 kcal.
Difference: 1.32 − 0.99 = 0.33 kcal for the illustrative 330 ml serving. These are arithmetic outputs from rounded label values, not precise laboratory energy measurements. [2] [3]
The useful conclusion is that both listed values are very low. Turning a difference of a third of a kilocalorie in this example into a broad health ranking would overstate what the comparison shows. A choice based on the flavour you enjoy is answering a different question from the label calculation.
Both compared UK regular products list 0 g sugars per 100 ml. Taste can guide the choice between them; “Diet” does not mean this drink has sugar while “Zero” does not. [2] [3]
Neither regular product in this comparison meets that brief. Look specifically for a caffeine-free version and confirm its label; sugar-free and caffeine-free are different properties. [2] [3]
Confirm the country, full product name and pack. It may be an imported, flavoured or differently formulated version. Use that pack’s ingredients rather than forcing it to match a table about the regular UK products.
No. They have different intended flavour profiles and the current UK ingredient lists differ. The shared absence of sugar does not make them the same formulation. [1] [2] [3]
No. Caffeine flavouring appears in the regular Zero Sugar ingredient list, just as it does in regular Diet Coke. A caffeine-free product is separately labelled. [2] [3]
The numerical product entries are 0.3 and 0.4 kcal per 100 ml. This guide keeps those very small published figures visible rather than treating marketing shorthand as a precise measurement. [2] [3]
Sources reviewed on 6 October 2026. Worked examples and exercises were written for this article. AI assisted preparation; the featured image is an AI-generated editorial illustration.
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