The UK traffic light system colours fat, saturates, sugars and salt as green, amber or red against per-100g thresholds set by the Food Standards Agency.

How to Read a UK Nutrition Label in 2026: A Plain English Guide

We have all been there: standing in the supermarket aisle, turning a packet over, and facing a grid of numbers that seems to blur together. You want to make a sensible choice—for your waistline, your blood pressure, or just for a balanced family tea—but the label feels like a puzzle. This guide is here to calm that moment.

By the end, you will know exactly what each block of numbers means, which colours and percentages matter most for your health goals, and the small print tricks worth spotting in 2026. It is not about memorising rules; it is about gaining a quiet confidence to read any packet with clarity.

The two labels on every UK packet, front and back

UK prepacked food packaging can carry up to two distinct nutrition labels, each with a different purpose. The first, on the back of the pack, is a legal requirement. This nutrition declaration must list seven key components: energy (in both kilojoules and kilocalories), fat, saturates, carbohydrate, sugars, protein, and salt. All values are given per 100 grams or 100 millilitres, providing a standard measure for comparison. Some products also voluntarily include a ‘per portion’ column.

The second label, on the front of the pack, is the familiar traffic light system. This is voluntary in the UK, but its adoption is widespread among major supermarkets and many manufacturers. It provides a quick visual snapshot, covering four nutrients of public health concern: fat, saturates, sugars, and salt, alongside the energy value. Think of the back label as the detailed technical sheet for accurate comparison, and the front label as the quick-reference guide for your trolley decision.

How the UK traffic light system actually works

The traffic light system uses red, amber, and green colours to indicate whether a food is high, medium, or low in certain nutrients. The assessment is based on the amount per 100 grams of the food. It is a per-100g system, not per portion. The thresholds are set to help you make swift comparisons. A green light means the nutrient is low, amber means medium, and red means it is high. This applies to fat, saturates, sugars, and salt. The energy value is displayed but not colour-coded. drinks have separate, lower thresholds calculated per 100 millilitres.

Fat, saturates, sugars and salt thresholds in plain numbers

For every 100 grams of food, the traffic light colours are triggered at these points. For fat: green is up to 3.0g, amber is 3.1g to 17.5g, and red is over 17.5g. For saturates: green up to 1.5g, amber 1.6g to 5.0g, red over 5.0g. For sugars: green up to 5.0g, amber 5.1g to 22.5g, red over 22.5g. For salt: green up to 0.3g, amber 0.31g to 1.5g, red over 1.5g. Remember, for drinks, the per-100ml thresholds are lower—for example, sugar is red above 11.25g per 100ml.

How to use the colours without getting paranoid

A row of red lights can feel alarming, but context is key. Use the traffic lights as part of a whole-day, whole-diet picture. Aim for mostly greens and ambers across the foods you eat regularly. An occasional red on a treat food is part of normal eating. The concern is when a food you eat daily—like a particular cereal, snack, or ready meal—shows multiple reds. This is where cumulative intake of saturated fat, sugar, and salt can contribute to raised blood pressure, weight gain, or higher LDL cholesterol over time. Cheese, for instance, is often high in fat and saturates, but a matchbox-sized portion as part of a varied diet is different from eating a sharing bag of crisps high in fat and salt every day.

What the percentages mean (Reference Intakes)

The Reference Intake, or RI, is a set of daily nutritional values used on UK labels. They are based on the average requirements for an adult woman engaging in average physical activity. The standard figures are: 2000 kcal for energy, 70g for fat, 20g for saturates, 90g for total sugars, and 6g for salt. You will often see a percentage RI on the front of pack. This tells you what proportion of that daily reference amount is provided by one portion of the food. So, a snack bar with 25% RI for sugars contains a quarter of an average woman’s daily sugar guide in one go.

You need to remember that RIs are a general guide for comparison, not a personal target to hit. They are set for adults; children have lower needs. The NHS recommends a maximum of 6g of salt per day for all adults, and lower amounts for children: 3g for 4-6 year olds, 5g for 7-10 year olds, and 6g for those 11 and over.

Reference Intakes are general guides for the average adult, not personal targets. Always consider your overall dietary pattern.

Per 100g vs per portion, where the small print hides

The per 100g column is your most reliable tool for comparing similar products. It allows you to see which yoghurt has less sugar or which soup has less salt, regardless of the package size or the manufacturer’s suggested portion. The per portion column is optional and uses a portion size chosen by the manufacturer. This is where you need to be alert. A cereal might list a 30g portion, but most people pour significantly more. A sharing bag of crisps might show nutrition per 25g serving, implying the whole bag is for sharing, when in reality many people eat it alone.

If a front-of-pack label looks healthy but the portion size seems tiny, do the maths. A simple trick is to use your phone’s calculator: divide the weight of the amount you actually eat by the printed portion size to get a multiplier, then multiply the calories and nutrients by that number.

The ingredients list, allergens and small claims

The ingredients list is your map of what is actually in the food. Ingredients are listed in descending order by weight at the time of manufacture. The first three ingredients usually tell you the most about a product. If sugar, glucose syrup, or refined oils appear in the top three of a savoury item like bread or pasta sauce, it is worth taking note.

You will also see nutrition and health claims like ‘low fat’, ‘source of fibre’, or ‘high in protein’. These are strictly regulated by the GB Nutrition and Health Claims Register, meaning manufacturers can only use approved wording. Remember, ‘low fat’ does not automatically mean low sugar, and ‘low sugar’ does not mean low calorie.

Calorie labelling on UK menus and what is coming in 2026

Since April 2022 in England, food businesses with 250 or more employees must display the calorie content of items on menus at the point of choice. This applies to most chain restaurants, takeaways, and cafes. They must also include a statement that “adults need around 2000 kcal a day.” The government scheduled a review of these rules for 2026, considering whether to extend the requirement to smaller businesses. As of 2026, only large operators are covered, so your independent local cafe is not required to show calories.

Scotland, Wales, and Northern Ireland have not introduced identical rules, though consultations have occurred. Some early research, such as a 2024 Cambridge Public Health Nutrition study, suggests the main impact has been on restaurants reformulating dishes to appear under certain calorie thresholds, rather than a major shift in consumer ordering.

Best before vs use by, country of origin and freezing

Understanding date labels can reduce food waste and keep you safe. ‘Best before’ is a quality date. The food is safe to eat after this date, but its flavour, colour, or texture may have deteriorated. ‘Use by’ is a safety date. You should not eat food past its use by date, even if it looks and smells fine. This is especially important for high-risk foods like cooked meats, ready meals, dairy, and smoked fish, where bacteria like listeria can grow to dangerous levels without any visible signs.

Country of origin must be shown on certain foods, including beef, pork, poultry, fish, honey, olive oil, and fresh fruit and vegetables. If you freeze food at home, you extend its life. The Food Standards Agency recommends labelling it with the date frozen and consuming most items within three months for best quality, though they remain safe if kept continuously frozen.

Frequently Asked Questions

Are traffic light labels mandatory in the UK in 2026?

No. Front-of-pack traffic light nutrition labels remain voluntary in the UK as of 2026. However, their use is very common among major supermarkets and many food manufacturers. The mandatory element is the back-of-pack nutrition declaration table required on all prepacked food under retained EU law. Public health organisations have periodically called for traffic lights to be made compulsory.

What does RI stand for on UK food labels?

RI stands for Reference Intake. It represents the daily amount of a nutrient considered adequate for an average adult woman with an average activity level. The standard UK RIs are 2000 kcal for energy, 70g fat, 20g saturates, 90g sugars, and 6g salt. The percentage RI shown on a label indicates how much of that daily guide is in one portion of the food.

How many grams of sugar is high on a UK label?

Under the UK traffic light system, a food is rated red (high) for sugar if it contains more than 22.5g of sugars per 100g. The green (low) threshold is up to 5.0g per 100g, and amber (medium) is between 5.1g and 22.5g. For drinks, the thresholds per 100ml are lower: red is over 11.25g.

Is per 100g or per portion more useful when comparing two products?

Always use per 100g for direct comparison. Portion sizes are set by manufacturers and can vary wildly between brands, making per-portion numbers an unreliable like-for-like measure. The per-100g column allows you to objectively see which product has less sugar, salt, or fat per standard weight.

Why do some packets show per 100g and per portion both?

Per 100g is a legal requirement on prepacked food in the UK. Per portion information is optional. Manufacturers often include it to make the nutritional profile seem more favourable, typically by suggesting a small portion size. It is essential to check whether that portion matches what you would realistically eat.

What is the difference between best before and use by?

Best before relates to quality. The food is safe to eat after this date but may not be at its best in terms of taste or texture. Use by relates to safety. You should not eat food after its use by date, as it could pose a food safety risk, even if it looks fine. This is particularly critical for perishable items like meat and dairy.

This article is informational only and does not replace personalised advice from your GP, pharmacist, or another qualified healthcare professional.