How to Read a Nutrition Label — A Plain-English Guide
The nutrition label on the back of a food package contains a lot of information — and most people skip past it. But understanding what those numbers actually mean can make a genuine difference to how you eat. This guide walks through every section, in plain English, so you can make properly informed choices without needing a nutrition degree.
Serving Size — The Starting Point
The very first thing to check is the serving size. All the numbers on the label — calories, fat, sugar, everything — are given per serving. If the packet says 200 kcal per serving but the serving size is 30g and you eat 90g, you have consumed 600 kcal. This is the single most common source of confusion with food labels.
UK labels typically also show figures per 100g (or 100ml for drinks), which makes it much easier to compare different products directly — regardless of serving size differences.
Calories (Energy)
Energy is listed in kilocalories (kcal) — what most people call "calories" — and sometimes also in kilojoules (kJ). The average adult needs roughly 2,000 kcal per day (women) or 2,500 kcal (men), though this varies significantly by age, activity level, height and weight.
The calorie count tells you how much energy is in the food, but it says nothing about its nutritional quality. 200 kcal of nuts is very different from 200 kcal of sweets in terms of its effect on hunger, blood sugar, and health.
🍎 Know your numbers: Use Toolify's Calorie Estimator to calculate your personal daily calorie needs, and the Macro Calculator to set protein, carb and fat targets.
The Main Nutrients
Fat (and saturated fat)
Total fat is broken down into saturated and unsaturated fats. Saturated fat is the one to watch — high intake is linked to raised LDL cholesterol and cardiovascular risk. The UK government recommends no more than 20g of saturated fat per day for women and 30g for men. Per 100g, anything above 5g of saturated fat is considered high.
Unsaturated fats (mono and polyunsaturated) are generally beneficial and should not be lumped in with saturated fat in your thinking.
Carbohydrates (and sugars)
Total carbohydrates include starches, fibre and sugars. The sugars figure includes both naturally occurring sugars (from fruit, milk) and added sugars. It is the added sugars that are most relevant to health — but the label does not distinguish between them. As a guide, anything above 22.5g of total sugars per 100g is high; below 5g is low.
Fibre
Dietary fibre supports digestive health, feeds beneficial gut bacteria, helps you feel full, and is linked to lower risk of heart disease and type 2 diabetes. Most people in the UK eat far less than the recommended 30g per day. A product with 6g of fibre per 100g is considered high in fibre.
Protein
Protein is essential for muscle repair, immune function, and satiety. The UK reference nutrient intake for adults is 0.75g per kilogram of body weight — so a 70kg person needs around 52g per day, though active individuals and older adults benefit from more. Labels show protein per serving and per 100g.
Salt
Older labels showed sodium; UK labels now show salt (1g of sodium = 2.5g of salt). The recommended maximum is 6g of salt per day. Anything above 1.5g of salt per 100g is considered high; below 0.3g is low.
Traffic Light Labels
Many UK food products use a voluntary front-of-pack traffic light system that colour-codes key nutrients:
At a glance, aim for mostly green and amber. An occasional red is fine — the context of your overall diet matters far more than any single food. A product with red for fat but green for saturated fat, sugar and salt is a different proposition from one that is red across the board.
Percentage Reference Intakes (%RI)
Many labels include a % Reference Intake figure, which shows what percentage of a reference adult's daily needs each nutrient represents. These are based on a 2,000 kcal diet. If a serving provides 25% RI for saturated fat, that is a quarter of the recommended daily maximum in one portion.
Ingredients List
Ingredients are listed in descending order by weight — the first ingredient is the most abundant. A loaf of bread listing "water" as the second ingredient after "wholemeal flour" is telling you something very different from one that lists "refined wheat flour" first followed by "sugar" and "vegetable oil". The ingredients list often tells you more about a product's quality than the nutrition panel does.
Also look for allergen information — the 14 major allergens must be highlighted (typically in bold) within the ingredients list under UK law.
Putting It Together
You do not need to analyse every label in depth at every shop. But building a habit of checking the per-100g figures for saturated fat, sugar and salt — and glancing at the ingredients list — takes about 10 seconds and quickly builds a strong intuition for what you are eating.