How Many Calories in a Diet Coke?
A 330 ml can of Diet Coke is about 1.3 calories. Per 100 ml the figure is 0.4, and a 500 ml bottle comes to roughly 2. So the honest answer to how many calories in a Diet Coke is: none that will ever matter to your day. The number that will is on the red can next to it.
On this page
- Diet Coke quick facts
- Why a can is not quite zero
- The 139 calories you are actually avoiding
- One can a day, for a year
- Diet Coke, Coke Zero and the rest of the shelf
- What a zero drink does not settle
- Most popular Coca-Cola products in the United Kingdom
- Diet Coke FAQs
Diet Coke quick facts
The only useful way to present this label is next to the one it replaced.
| Per 330 ml can | Diet Coke | Coca-Cola |
|---|---|---|
| Energy | about 1.3 kcal / 6 kJ | 139 kcal / 582 kJ |
| Carbohydrates | 0 g | 35 g |
| – of which sugars | 0 g | 35 g |
| Protein | 0 g | 0 g |
| Fat | 0 g | 0 g |
| Salt | about 0.07 g | – |
| Share of a 2,000 kcal day | under 1% | 7% |
| Share of the 90 g sugars reference | 0% | 39% |
Per 100 ml that is 0.4 kcal for Diet Coke against 42.1 for the full-sugar version, based on a UK label consensus drawn across dozens of products. Every other row on the Diet Coke side is a flat zero. There is no protein, no fat, no fibre and no sugar in it, and the reference intake percentages round to nothing.
Serving by serving: a can is about 1.3 kcal, a 500 ml bottle about 2, and a full 2 litre bottle about 8. Eight calories across two litres sits well inside the rounding error of anything you eat that day.
Why a can is not quite zero
Nutrition labelling rounds. Below a certain threshold, an energy value per 100 ml is declared as zero even when it is not literally zero, which is how a drink containing a trace of carbohydrate and flavouring ends up printed as 0 kcal.
Aggregate enough UK product records and the underlying figure resolves to about 0.4 kcal per 100 ml. Multiply by 3.3 and a can is 1.3 calories rather than 0. It is a distinction with no practical consequence, and it is worth knowing anyway, because it explains why different databases show 0, 0.3 or 0.4 for what looks like the same drink.
Salt behaves the same way. At roughly 0.02 g per 100 ml, a can carries about 0.07 g, which is roughly 1% of the 6 g daily maximum. Present, technically. Irrelevant, practically.
If you are logging, put a can in at 1 calorie or leave it out. Both are correct to within a rounding error, and neither will move a daily total.
The 139 calories you are actually avoiding
Here is where this page earns its place. A 330 ml can of ordinary Coca-Cola is 139 calories and 35 g of sugar. That sugar figure is 39% of the daily reference intake, taken from a drink that does not fill you up and rarely counts as food in anyone's head.
Verified nutrition data
Numbers on this page come from CoFID, the UK government’s Composition of Foods Integrated Dataset, and from manufacturer labels where a branded product is named. Last verified August 2026. How we verify our data →
Thirty-five grams in a single can. Almost the entire day's allowance for sugars, in something you can finish in under a minute standing at the fridge.
The 139 calories are the smaller half of the story, because 139 is only 7% of a 2,000 calorie day. Plenty of foods cost more. What makes the regular can distinctive is the ratio: it delivers 39% of a nutritional limit while delivering 7% of the energy budget and none of the satisfaction of a meal.
Switch to Diet Coke and both numbers collapse to nothing at once. That is the actual transaction, and it is a good one on this specific measure. Anyone framing the decision as "1.3 calories versus 139" is understating it.
One can a day, for a year
Take the daily habit and run it out.
A can of regular Coca-Cola every day for a year is 50,735 calories and 12.8 kg of sugar. Twelve and a half kilos, from one can a day, ordered and drunk without thinking about it once.
The same year on Diet Coke is roughly 475 calories in total and no sugar at all. Not a meal's worth. Not a day's worth. Under five hundred calories across three hundred and sixty-five drinks.
That gap is why the swap keeps being recommended and why it keeps working for people who make it. It is also a reminder about scale. Nobody changes anything by fretting over the 1.3 calories in the can they are holding. The lever is which can they reach for, repeated.
Two smaller versions of the same arithmetic. Regular Dr Pepper runs 28.8 kcal per 100 ml, so a 330 ml can is about 95 calories and 23.8 g of sugar, noticeably lighter than Coca-Cola but far from free. And a bottle rather than a can changes the sums: 500 ml of full-sugar cola is 211 calories and 53 g of sugar, more than half a day's sugars reference in one container.
Diet Coke, Coke Zero and the rest of the shelf
| Per 100 ml | Calories | Sugar |
|---|---|---|
| Diet Coke | 0.4 kcal | 0 g |
| Coca-Cola Zero Sugar | about 0.3 kcal | 0 g |
| Diet Coke No Caffeine | about 0.3 kcal | 0 g |
| Pepsi Max | about 0.4 kcal | 0 g |
| Dr Pepper Zero | about 0.5 kcal | 0 g |
| Dr Pepper, regular | 28.8 kcal | 7.2 g |
| Coca-Cola, regular | 42.1 kcal | 10.6 g |
Diet Coke and Coke Zero are genuinely different products. The sweetener blends differ and so does the flavour brief, which is why people have firm opinions about which is which. On calories they are indistinguishable: 0.4 against 0.3 per 100 ml, a gap of a third of a calorie in a can.
Pepsi Max lands in the same place at roughly 1 calorie a can. Dr Pepper Zero is a rounding fraction higher at 0.5 per 100 ml and still under 2 calories a can. Choose between the zero drinks on taste, because there is nothing on the nutrition panel to choose between.
The regular versions are where the spread opens up. Dr Pepper at 28.8 kcal per 100 ml is a third lighter than Coca-Cola's 42.1, with 7.2 g of sugar per 100 ml against 10.6. Lighter is not light: a can is still around 95 calories and 24 g of sugar.
Our take: on calories and sugar, Diet Coke is free and you can treat it as free when logging. If you drink a full-sugar cola every day, that is the single easiest 139 calories and 35 g of sugar to remove from a diet, and the swap costs you nothing but a preference. If you already drink the diet version, there is no further calorie saving to find here; go and look at what is on the plate instead.
What a zero drink does not settle
A nutrition label answers two questions: how much energy, and how much of each nutrient. On both, Diet Coke reads as close to nothing as a flavoured drink gets.
It does not answer everything people mean when they ask whether the drink is a good idea. Caffeine content, dental considerations and how a strongly sweet taste sits alongside the habit of wanting sweet things are all real questions, and none of them is a calorie question. This page is about the calories, and on that count the verdict is straightforward.
If it is the caffeine you are after rather than the cola, a cup of tea and an energy drink such as Monster sit at opposite ends of the calorie scale, and both have their own pages here. And if you reach for a can because you are hungry rather than thirsty, a protein shake is the version of that reflex that brings something back.
One practical note that does belong here: as a mixer, a diet drink means the entire calorie count in the glass comes from the spirit. That is genuinely useful when logging a night out, because the mixer stops being a variable and the measure becomes the only thing to record.
The other trap is asymmetry. People who drink Diet Coke tend to log it carefully out of habit and then wave through the occasional full-sugar can at a pub or a barbecue. The 1.3 is not worth typing. The 139 always is.
Most popular Coca-Cola zero-sugar products in the United Kingdom
Ranked by how widely each product appears among foods sold in the United Kingdom, from the BodyPal food database of over 3.3 million products. Calories are the figures printed on each label. Regular Coca-Cola is 42 kcal per 100 ml on the same shelf.
| Product | Calories (per 100 ml) |
|---|---|
| Diet Coke | 0.4 kcal |
| Diet Coke No Caffeine | 0.3 kcal |
| Coca-Cola Zero Sugar | 0.3 kcal |
| Cherry Coke Zero | 1 kcal |
| Sprite Zero | 1 kcal |
Brand popularity: BodyPal food database. Nutrition: manufacturer labels.
Diet Coke FAQs
How many calories in a can of Diet Coke?
About 1.3 calories in a 330 ml can, from 0.4 kcal per 100 ml. Labels declare it as zero because of rounding rules, and for logging purposes zero is close enough. There is no sugar, protein or fat in it at all.
Diet Coke or Coke Zero: which has fewer calories?
They are effectively identical: 0.4 kcal per 100 ml for Diet Coke and about 0.3 for Coca-Cola Zero Sugar. That is a difference of roughly a third of a calorie in a can. The sweetener recipes differ, which is why they taste different, but the nutrition panels do not.
Does Diet Coke have sugar in it?
No, the sugars line is 0 g. A 330 ml can of regular Coca-Cola carries 35 g by comparison, which is 39% of the 90 g daily reference intake for sugars in a single can.
How much caffeine is in Diet Coke?
Caffeine is named in the ingredients, but Coca-Cola does not print a milligram figure for it on the Diet Coke product page, so any number quoted elsewhere is not coming from the label. A caffeine-free version exists and is nutritionally the same drink, at roughly 0.3 kcal per 100 ml.
How many calories in a 500ml Diet Coke?
About 2 calories. A 2 litre bottle works out at roughly 8. Both figures sit inside the rounding error of a normal day's food, so there is no practical reason to count them.
How many calories does swapping to Diet Coke save?
About 139 calories and 35 g of sugar per can. Over a year of one can a day that is 50,735 calories and 12.8 kg of sugar avoided, against roughly 475 calories in total for the same year on Diet Coke.
Diet Coke or Pepsi Max?
Nothing separates them on calories. Diet Coke is 0.4 kcal per 100 ml and Pepsi Max about the same, which is roughly 1 calorie a can either way. Neither contains sugar. Pick on taste.
Is Diet Coke bad for you?
On the two things a nutrition label measures, it is as close to neutral as a flavoured drink gets: about 1.3 calories a can, no sugar and around 0.07 g of salt. Questions about sweeteners, caffeine and teeth are separate from the calorie question and are not answered by the panel on the can.
Similar foods
- Pepsi Max — about 1 kcal a can
- Cup of tea — 13 kcal with milk
- Cappuccino — 68 kcal per regular cup
- Latte — 68 kcal a mug at home
- Lucozade Sport — 135 kcal a 500 ml bottle
- Can of Coke — 139 kcal a 330 ml can
Log the red cans, ignore the silver ones
BodyPal reads a drink from a photo of the label, so the 139 calorie can gets counted and the 1.3 calorie one does not slow you down.
