Ingredients run from most to least.

Order means amount

On UK prepacked food, ingredients are listed in descending order of weight — what the manufacturer put in most comes first, down to the smallest addition. Ingredients are weighed as they went in at manufacture, water included. Source: GOV.UK food labelling guidance (opens in a new tab).

That makes the first few entries a quick character sketch of the product: a biscuit whose list opens "wheat flour, sugar, vegetable oil" is mostly those three, whatever the front of the pack suggests. A flavour named only at the tail is present in trace amounts.

It also makes the list a quiet comparison tool. Two jars of tomato pasta sauce can share a name and a price while opening on different ingredients — tomatoes first on one, water or sugar first on the other. The order is the first honest difference between them.

The list itself must sit under a heading containing the word "ingredients", and some foods are exempt from needing a list at all — single-ingredient products like plain flour, or fresh unpeeled fruit and vegetables, among them. Source: GOV.UK food labelling guidance (opens in a new tab).

Descending weight order is the default rather than an absolute: the rules permit regulated variations for cases like dehydrated or reconstituted ingredients, where what went in and what you get weigh differently. Treat order as the strong signal it almost always is. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

Allergens in emphasis

Any of the 14 allergens that must be declared has to stand out in the list — typically bold, capitals, underlining or a contrasting colour. Scan for emphasis first, then read the words around it. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

Two edge cases. If the food's name already names the allergen — a carton of milk, a jar of peanut butter — separate emphasis is not required. And food packed on the premises before you select it ("prepacked for direct sale", the rule often called Natasha's Law since October 2021) must carry the food's name and a full ingredients list with allergens emphasised too. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

One more rule worth knowing: the emphasis must appear every time the allergen appears — including inside those bracketed compound ingredients. A list that bolds milk once but not in the "butter" it repeats later is not playing by the rules. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

When a percentage appears (QUID)

Some ingredients carry a percentage — the "quantitative ingredient declaration", or QUID. It is required when an ingredient is in the food's name ("blackberry and apple pie"), emphasised on the label by words or pictures, usually associated with the name, or is what makes the product what it is. Source: GOV.UK food labelling guidance (opens in a new tab).

The guidance's own example is telling: lasagne made with pork must show the pork percentage, because that is what distinguishes it from lasagne made with beef. Read a QUID as the answer to "how much of the headline ingredient is actually in this?" — and compare it across brands, where it can differ quietly. Source: GOV.UK food labelling guidance (opens in a new tab).

Compound ingredients in brackets

An ingredient that is itself made of several things can appear with its own bracketed sub-list — "chocolate chips (cocoa mass, sugar, cocoa butter)" or "biscuit crumb (wheat flour, sugar, vegetable oil)". The bracket is part of the list, following the same descending logic.

This is where allergen-hunting gets its second pass: the declared allergens inside a compound ingredient must still be emphasised. If you check for allergens, read inside every bracket, not just the top level. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

There is a narrow exemption: a compound ingredient making up under 2% of the finished product can appear by name alone — though the 14 allergens inside it must still be declared, and additives doing a job in the compound still have to be named. When in doubt about a bracket, ask the maker rather than guessing. Source: GOV.UK PPDS labelling guidance (opens in a new tab).

E numbers and function words

Additives appear by their function word plus a name or E number — entries like "colour: beetroot red" or a preservative followed by its number. An E number marks a substance authorised for use in food, not a warning level; the function word tells you what job it does. Source: GOV.UK food labelling guidance (opens in a new tab).

Flavourings are the loosest entry — "flavouring" or "natural flavouring" can cover a preparation rather than a single substance. And where an ingredient cannot practically be broken down further, the guidance lists exemptions rather than pretending otherwise. Source: GOV.UK food labelling guidance (opens in a new tab).

Two small footnotes that occasionally matter. Engineered nanomaterials must be marked with the word "nano" in brackets after the ingredient name — rare, but unmissable when it appears. And irradiated ingredients must say so, even when they arrive inside a compound ingredient (irradiated milk inside cheese, say). Source: GOV.UK food labelling guidance (opens in a new tab).

Declarations that sit beside the list

Some ingredients trigger mandatory wording elsewhere on the pack, not just an entry in the list. Foods containing sweeteners must say "with sweetener(s)" beside the food's name — "with sugar(s) and sweetener(s)" if both are present — and aspartame specifically requires a "contains a source of phenylalanine" warning, vital reading for people with phenylketonuria. Source: GOV.UK food labelling guidance (opens in a new tab).

Drinks containing more than 150mg of caffeine per litre must carry a "High caffeine content" warning with the amount in brackets, and caffeine added to other foods needs a "Contains caffeine" note. One exemption runs the other way: drinks over 1.2% alcohol by volume need not carry an ingredients list at all — though allergen rules still apply, which is why a wine label can flag sulphites without listing anything else. Source: GOV.UK food labelling guidance (opens in a new tab).

What the list can't tell you about a serving

The ingredients list tells you what went in, in order — not how much of anything beyond the QUID percentages, and not what a portion of it looks like. For amounts, the nutrition table's per-100g and per-portion columns are the other half of the label (that guide here); for safety dates, use-by and best-before are their own system.

And a boundary worth repeating: a photo of the food cannot read its label. If the pack is in your hand, read it — it outranks any lookup. A Food Says Hi lookup can still help when there is no label — naming the unfamiliar dish, and taking what you remember of the label in the note — but ingredients, allergens and dates belong to the pack and the people selling it. What a food photo can tell you.