How to Read Food Labels in the UK

The two parts of a UK food label

Every pre-packaged food sold in the UK is required by law to display a nutrition information table. Most also display a front-of-pack traffic light panel, though this is voluntary.

Back-of-pack nutrition table (mandatory)

This must show, per 100g or 100ml:

• Energy in kilojoules (kJ) and kilocalories (kcal)
• Fat (total)
• Saturates (saturated fat)
• Carbohydrate (total)
• Sugars (total)
• Protein
• Salt

Fibre is not mandatory on the back-of-pack table. Manufacturers include it voluntarily. When it is absent, it is usually because the fibre content is low or negligible. See dietary fibre for what the figure means and why it matters.

Vitamins and minerals may also be listed voluntarily, expressed per 100g and as a percentage of the Nutrient Reference Value (NRV).

Front-of-pack traffic light panel (voluntary)

Most major UK supermarkets and many branded food manufacturers display a colour-coded panel on the front of the pack showing the same five values per portion: energy, fat, saturates, sugars, and salt. The colours, red, amber, or green, tell you whether the level of each nutrient is high, medium, or low.

This panel is voluntary, but the Food Standards Agency (FSA) recommends a specific format and the major UK retailers (Tesco, Sainsbury's, Asda, Morrisons, Waitrose, Aldi, Lidl, M&S, Co-op) have all adopted it. Some smaller brands and many products imported from outside the UK do not use it. In those cases, the back-of-pack table is all you have.

Understanding calories: kJ and kcal

Energy on a UK food label is shown in two units: kJ (kilojoules) and kcal (kilocalories). These are two different units measuring the same thing.

• kcal is what most people call "calories" in everyday speech. When someone says a biscuit contains 90 calories, they mean 90 kcal.
• kJ is the SI (scientific) unit of energy. One kcal equals 4.18 kJ.

You only need to use one. For most people in the UK, kcal is the more useful figure.

Reference intakes for energy: women, 2,000 kcal per day (8,400 kJ); men, 2,500 kcal per day (10,500 kJ). These are population averages. Your actual needs depend on your age, size, and activity level. They are the figures the label's % RI percentages are calculated against (using the women's figure of 2,000 kcal as the baseline).

The traffic light system. Colours and thresholds

The traffic light colours are based on the nutrient content per 100g for solid foods and per 100ml for drinks. The exact thresholds are set by the government and the Food Standards Agency.

Drink thresholds are roughly half of food thresholds because drinks contain more water and therefore lower concentrations of nutrients. This is why a fruit smoothie with 12g of sugar per 100ml gets a red traffic light even though that sugar level in a solid food would be amber.

What the colours mean in practice

• Green. The food is low in that nutrient. More greens generally means a healthier product.
• Amber. The food is neither high nor low. You can eat amber foods most of the time as part of a balanced diet.
• Red. The food is high in that nutrient. It does not mean you cannot eat it, but it should be consumed less often and in smaller amounts. A product can have red for fat but be nutritious in other ways. Plain salted nuts, oily fish in olive oil, and full-fat plain yogurt all show red lights for fat or saturated fat but remain part of healthy eating patterns.

A product with all green lights will be low in fat, saturated fat, sugar, and salt, but this alone does not make it nutritious. A plain sparkling water would score all green, and so would a diet drink. Always consider the whole label, not just the colour band.

Reference Intakes (% RI). What the percentages mean

Alongside the traffic light colours, front-of-pack labels show a percentage of Reference Intake (% RI) for each nutrient. This tells you how much of an average adult's recommended daily amount of that nutrient is in one portion of the product.

Important notes on Reference Intakes

• RI is not the same as a target. It is a guideline for an average adult woman doing an average amount of physical activity. Your personal needs differ by age, sex, weight, and activity level.
• The sugars RI (90g) is for total sugars, which includes naturally occurring lactose in dairy and intrinsic sugars in whole fruit. It is not the same as the SACN free sugars limit of 30g per day. A product can show a low % RI for sugars while still being high in free sugars, if those sugars are added rather than naturally occurring. See free sugars explained for the difference.
• There is no RI for fibre on food labels, even though the SACN recommendation (30g per day) is just as important as the salt or sugar limits. If a product contains fibre, you will usually find the figure only in the back-of-pack table, not on the front. See dietary fibre for why this matters.
• % RI is calculated on the manufacturer's portion size, which may be smaller than what you actually eat. Always check what the stated portion size is and adjust accordingly.

How to use % RI

A useful rule of thumb: if a single product contributes more than 20% RI of a nutrient in one portion, it is a significant source of that nutrient. If it contributes more than 30% RI, it is a very significant source. A product contributing 50% of your daily salt in one portion (not unusual for ready meals and soups) means the other meals in that day need to be very low in salt not to exceed the daily limit.

Per 100g vs per portion. Which should you use?

This is the most practical issue when comparing products, and it causes significant confusion.

Per portion tells you the nutritional content of one manufacturer-defined serving. The problem is that portion sizes are set by manufacturers and are frequently smaller than the amount most people actually eat. Sometimes dramatically so.

Per 100g (or per 100ml for drinks) is the standardised measurement that allows fair comparison between products regardless of package size or suggested portion.

Always use per 100g when comparing two products. If you are choosing between two pasta sauces, two breakfast cereals, or two varieties of bread, look at the per 100g column for each one. A product with a smaller suggested portion can appear lower in sugar, fat, or salt per portion than it actually is relative to its competitor.

Use per portion when managing daily intake. Once you have chosen a product and want to track how it fits into your daily totals, the per portion figure (combined with your realistic portion size) is what matters for a food diary. Just verify that the manufacturer's portion matches what you are actually putting on your plate.

A worked example

Two breakfast cereals both have a 30g suggested serving. Cereal A has 12g of sugar per 100g; Cereal B has 8g per 100g. Both show their per-portion sugar as 3.6g and 2.4g respectively. The difference looks small. But if you eat 60g (a realistic serving for many people), Cereal A delivers 7.2g of sugar and Cereal B delivers 4.8g. Per 100g reveals the difference; per portion can obscure it.

The ingredient list. The most honest part of the label

The nutrition table tells you how much of each nutrient is in a product. The ingredient list tells you what that product is actually made of, and it is often more revealing.

The rules

1. Ingredients are listed in descending order of weight. The first ingredient makes up the largest proportion of the product. If sugar is the first or second ingredient, the product is predominantly sugar by weight.
2. Ingredients are listed as sold, not as prepared. So a product that is mostly water when cooked may list water first.
3. Compound ingredients (ingredients that are themselves made from multiple components) must list their own sub-ingredients in brackets. For example: "tomato sauce (tomatoes, sugar, salt, modified starch)". The brackets tell you what is in the sauce.
4. Allergens must be emphasised. They must appear in bold, italic, underlined, or otherwise visually distinct from the surrounding text. This is a legal requirement.
5. Sugar appears under many names. Manufacturers sometimes split sugar across several synonyms to avoid any one appearing too prominently near the top of the list. See the sugar synonyms list for the full set.

What to look for

• If a product has five or more ingredients, especially ones you would not find in a home kitchen, it is likely to be NOVA Group 3 or 4 (processed or ultra-processed).
• If the first ingredient is a refined grain (white flour, corn flour, corn starch) rather than a whole grain, the wholegrain claim on the front is probably not as significant as it sounds.
• If you cannot pronounce or recognise most of the ingredients, it is almost certainly ultra-processed.
• For E numbers: see the additives directory for the full list of approved UK additives, with curated risk notes for the ones most worth knowing about.

Allergen information. What UK law requires

UK food law requires that any of the 14 major allergens present in a product must be emphasised in the ingredient list (typically in bold) and must be declared whenever they appear, including in compound ingredients and additives.

The 14 major allergens in UK law

Cereals containing gluten covers wheat, rye, barley, oats, spelt, kamut, and their varieties. Crustaceans covers prawns, crabs, and lobster. Molluscs covers mussels, oysters, and squid. Sulphites applies at concentrations above 10mg/kg or 10mg/litre. Tree nuts covers almonds, hazelnuts, walnuts, cashews, pecans, Brazil nuts, pistachios, macadamia nuts, and Queensland nuts.

Natasha's Law (2021)

Since October 2021, Natasha's Law has required that foods prepacked for direct sale (including sandwiches, salads, pastries, and other foods made and packaged on the same premises where they are sold, such as in supermarket delis, bakeries, and café counters) must carry a full ingredient list with allergens emphasised. Previously these only needed to provide allergen information on request.

"May contain" statements

These are voluntary precautionary statements used when a product is made in a facility that also handles a particular allergen, creating a risk of cross-contamination. "May contain traces of nuts" does not mean nuts are an ingredient. It means manufacturing conditions cannot guarantee their absence. For people with severe allergies, these statements should be treated as warnings. They are not regulated in their wording, which means they are applied inconsistently across manufacturers.

Date labels. Best before vs use by

These two date labels are frequently confused and the confusion contributes significantly to food waste.

Use by. A safety date. This is legally required on foods that deteriorate in a way that could be unsafe to eat, particularly dairy, meat, fish, and ready-to-eat products. You should not eat a product after its use by date, even if it looks and smells fine. Harmful bacteria can be present without obvious signs of spoilage.

Best before. A quality date. This tells you when a food is at its best quality. After this date, the food may not taste, smell, or look as good, but it is not necessarily unsafe to eat. Tinned goods, dried pasta, biscuits, cereals, and most ambient packaged foods carry a best before date. Eating food past its best before date is a matter of judgement (smell, appearance, taste) rather than a safety issue.

Sell by / Display until. These are stock management dates for retailers and have no legal or safety meaning for the consumer. You are not bound by them.

A significant volume of UK household food waste results from people discarding food at the best before date rather than using their senses to assess whether it is still good. The government and WRAP (Waste and Resources Action Programme) actively encourage consumers to understand the difference.

Front-of-pack claims. What they actually mean

The front of many food products carries marketing language designed to suggest health benefits. Some of these claims have precise legal definitions; others do not. Here is a plain-English guide to the most common ones.

Claims with legal definitions (must meet specific thresholds)

Claims without specific legal definitions. Use with caution

• "Natural" has no legal definition in UK food law. It can be applied freely by manufacturers.
• "Superfood" is not a regulated term. There is no legal definition or authorised health claim associated with it.
• "Healthy" is not a regulated nutrition claim under UK law, though advertising cannot be misleading.
• "Diet", when applied to soft drinks, has no specific nutritional definition beyond the presence of a sugar substitute.
• "Wholesome" has no legal definition.
• "Clean" (as in "clean eating") has no legal definition.

The "reduced" trap

"Reduced fat", "reduced sugar", and "reduced salt" only mean 30% less than the manufacturer's own standard product. If the original is very high, the reduced version may still be very high. A "25% less fat" crisp may have 20g of fat per 100g, still very high, because the original had 27g. Always check the per 100g figures against the traffic light thresholds in Section 3, not just the claim on the front.

Health claims (a different category)

A health claim states a relationship between a food or ingredient and a health benefit. For example, "beta-glucan contributes to the maintenance of normal blood cholesterol." Unlike nutrition claims, health claims must be pre-approved by regulators and backed by scientific evidence. If a claim sounds like it is promising a medical outcome, check whether it is an authorised health claim on the Great Britain Nutrition and Health Claims Register.

Health claims on food labels are not allowed to state that a food can prevent, treat, or cure any disease or medical condition.

The NOVA processing group. What the scanner adds

The mandatory nutrition table and the voluntary traffic light system tell you about the nutrients in a food. They do not tell you how processed the food is, and the degree of processing is increasingly understood to be an independent predictor of health outcomes, beyond what nutrients alone can explain.

The NOVA classification divides all foods into four groups based on the nature and extent of industrial processing:

• NOVA Group 1. Unprocessed or minimally processed whole foods (plain meat, fish, fruit, vegetables, eggs, plain dairy, plain oats, plain rice).
• NOVA Group 2. Processed culinary ingredients (oils, butter, salt, flour, vinegar).
• NOVA Group 3. Processed foods (tinned fish, cured meats, artisan cheeses, simple bread with four ingredients).
• NOVA Group 4. Ultra-processed foods (mass-produced bread, flavoured yogurts, breakfast cereals, ready meals, crisps, fizzy drinks, cereal bars, most fast food).

A product can have a reasonable-looking nutrition label (moderate calories, amber traffic lights) and still be a NOVA Group 4 ultra-processed product. The Food Insight scanner on this site assigns a NOVA group to every product it analyses, alongside the full ingredient list, additive flags, and an overall 0 to 100 nutrition verdict.

For a full explanation of what NOVA groups mean and why ultra-processed food matters, see the ultra-processed foods guide.

Common label confusions. Quick reference

A 30-second label-reading checklist

When you pick up a packaged food in a UK supermarket, here is a quick sequence that covers the most important information in under 30 seconds.

Key reference data at a glance