Voluntary, recommended, and consistent by agreement
The first thing to know about the colour-coded front of pack label is that no business is required to use it. It is a voluntary scheme, and its consistency comes from businesses choosing to follow a single recommended format rather than from a legal mandate.
Government guidance sets out that recommended format. It covers what has to appear, in what order, how the colours are assigned, and how the label should be presented so that different products can be compared without the reader having to interpret different designs.
The underlying figures are not new information. They come from the mandatory nutrition declaration on the back of the pack. The front of pack label is a presentation layer over data that is already there.
What the label contains
The recommended format combines several elements for each nutrient covered.
The nutrient amount, in grams, for a stated portion. This is the underlying figure.
The percentage of a reference intake that the portion contributes, which puts the number on a scale.
A colour band, assigned by applying defined criteria to the amount of the nutrient per 100g or 100ml, with separate treatment for portions above a defined size.
Energy, which is presented without a colour, because energy is not colour coded in the scheme.
The nutrients covered are fat, saturates, sugars and salt. That selection is the single most important thing to understand about the label, and the source of most misreadings of it.
| Element | In the scheme | Note |
|---|---|---|
| Energy | Yes | Shown without a colour |
| Fat | Yes | Colour coded |
| Saturates | Yes | Colour coded |
| Sugars | Yes | Colour coded |
| Salt | Yes | Colour coded |
| Fibre and protein | No | Available on the back of pack declaration |
| Vitamins and minerals | No | Voluntary declaration only, on the back |
| Additives and processing | No | Read the ingredients list |
Structure set out by this newsroom from the published rules named in the sources below. It is not a survey, a measurement or a market study.
What the scheme is designed for
The design intent is comparison at speed, within a category, at the shelf. The colours exist because a shopper choosing between two similar products in a few seconds cannot process eight numbers, and can process a pattern.
Everything about the format follows from that. The nutrients are few because a longer list would not be readable at a glance. The colours are assigned per 100g so that products of different pack sizes remain comparable. The format is standardised so that the comparison does not require re-learning a new design on each pack.
It follows that the label works best where it is used as intended, comparing two comparable products, and works least well where it is asked to do something else, such as ranking foods across categories or standing in for a judgement about a whole diet.
The limits, stated plainly
The scheme covers four nutrients plus energy. It does not cover fibre, protein, vitamins, minerals, additives, processing, portion realism, or anything about how a food is used within a meal or a week.
It is not a food quality rating. A colour is the output of applying a threshold to a number, and thresholds are lines drawn across continua. A product a fraction either side of a threshold gets a different colour for a difference that is inside the tolerance of the declared value itself.
It is also not personalised. The reference intakes used are labelling benchmarks based on a notional adult, and they take no account of age, size, activity or any medical circumstance.
None of this is a criticism of the scheme, which does not claim to do any of these things. It is a description of scope, and the mismatch between the scheme's scope and how it is often read is where the problems arise.
The portion question
The portion used on a front of pack label is chosen by the manufacturer, within general rules requiring it to be stated and to be meaningful. Colour, however, is generally assigned on the per 100g or per 100ml basis, with provisions for portions above a defined size.
This separation is deliberate and it protects the comparability of the colours. If colours were assigned per portion, a manufacturer could shift a colour by redefining a portion, and the scheme would immediately stop working as a comparison tool.
The consequence for a reader is that the colour is the comparable element and the gram figures relate to a portion someone else chose. Reading the colours across two packs is meaningful. Reading the gram figures across two packs is only meaningful if both assume the same portion.
Other marks on the front of a pack
The colour-coded label is one of several things that can appear on a front panel and it should not be confused with the others.
Nutrition claims, such as descriptions of a food as low in something, are a separate regime with their own thresholds. A product can carry a claim and a colour label at the same time, and they are assessed by different criteria.
Certification marks, assurance scheme logos and protected geographical symbols are different again, and say nothing about nutrition. Company-specific symbols and endorsements have their own status, which depends entirely on what stands behind them.
A useful discipline at the shelf is to ask, of every mark on a front panel, who defined it. The colour-coded label has a published government format. Many other marks do not.
Where this stops
This article describes a labelling scheme. It does not tell you what to eat, how to interpret a colour for your own circumstances, or whether any food is a good choice. Those are dietary questions, and they belong with the NHS or a registered dietitian rather than with a consumer publication or a colour on a pack.
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