Labels · Beginner guide

How to Read Nutrition Labels: A Beginner’s Guide

Check the portion, compare per 100 g, then look at energy, fat, saturates, sugars and salt. Read ingredients and highlighted allergens too.

UK example below; US labels use a different format, explained later.

Annotated UK-style label

Practice example · fictional breakfast cereal · not a real product

Fictional UK-style nutrition label with values per 100 g, per 30 g serving and percentage reference intake
Typical values 1	Per 100 g 2	Per 30 g serving 3	%RI* 4
Energy	1657 kJ / 396 kcal	497 kJ / 119 kcal	6%
Fat	12 g	3.6 g	5%
of which saturates	6.0 g	1.8 g	9%
Carbohydrate	60 g	18 g	—
of which sugars	20 g	6.0 g	7%
Fibre	6.0 g	1.8 g	—
Protein	9.0 g	2.7 g	—
Salt	0.80 g	0.24 g	4%

*Reference intake of an average adult (8400 kJ / 2000 kcal).

Typical values are averages for the product.
Per 100 g lets you compare different products fairly.
Per serving uses the manufacturer’s portion—your bowl may be bigger or smaller.
%RI shows how much of an average adult’s reference intake one serving provides. It is not a personal target.

How to read a nutrition label in 5 steps

Check the serving size and how many servings are in the pack.
Compare per 100g (or per 100ml for drinks) between similar products.
Look at energy in kcal and kJ—see Calories & Energy.
Check fat, saturates, sugars and salt, using traffic lights or high/low guides.
Read the ingredients: listed in order of weight, with allergens emphasised.

Per 100g vs per serving

UK and EU labels must give values per 100g or 100ml; many also show a per-serving column. Use per 100g to compare products, and per serving to understand what you might actually eat. On our practice label, 30g provides 119 kcal. If you pour 60g, double everything: about 238 kcal and 12g of sugars. Manufacturers choose their own serving sizes, so two brands may use different portions.

Sugar, fat and salt: high, medium or low

The NHS gives these guides for foods, per 100g. Anything between the two is medium.

NHS guides for foods (per 100g). Drinks use different criteria.
Nutrient	Low	High
Total fat	3 g or less	more than 17.5 g
Saturated fat	1.5 g or less	more than 5 g
Total sugars	5 g or less	more than 22.5 g
Salt	0.3 g or less	more than 1.5 g

UK traffic-light labels

Many UK packs use red (high), amber (medium) and green (low) colour coding on the front. This is voluntary UK guidance, so not every product has it, and it is not used in the same way in other countries. Our fictional cereal per 100g would look like this:

Fat
12 g
Medium
Saturates
6.0 g
High
Sugars
20 g
Medium
Salt
0.80 g
Medium

The NHS says a mostly green label generally means a healthier choice, while any red means that food is high in that nutrient and worth limiting. Colours are written as words above, too, so you don’t need to rely on colour alone.

How US labels differ

US packs carry a Nutrition Facts label from the FDA. Key differences:

Values are per serving (with servings per container); a per-100g column is not standard.
It shows Calories, not kJ, and lists sodium rather than salt.
%Daily Value is based on 2,000 calories a day as a general guide—not a personal need.
It lists added sugars and trans fat separately.

US serving sizes reflect amounts people typically eat, and the FDA stresses they are not a recommendation of how much to eat.

Ingredients and allergens

Ingredients are listed in descending order by weight, so the first few make up most of the product. In the UK, the NHS says pre-packed foods must highlight allergens, for example in bold, in the ingredients list; see the Food Standards Agency for allergy guidance. Phrases such as “may contain” are precautionary warnings; if you have an allergy, follow your clinician’s advice. Learn more in Lesson 7: Understanding Food Labels.

Common traps

Comparing a per-serving value with another product’s per-100g value.
Assuming “reduced fat” means low fat—it means less than a standard version.
Missing that a pack contains several servings.
Treating %RI or %DV as your personal target.

Label-reading checklist

Serving size and servings per pack
Per 100g/100ml to compare products
Energy in kcal (and kJ)
Fat and saturates: high is over 17.5g / 5g per 100g (UK, foods)
Sugars: high is over 22.5g per 100g (UK, foods)
Salt: high is over 1.5g per 100g (UK, foods)
Fibre and protein, where shown
Ingredients order and highlighted allergens

Source: NHS food labels guidance. Educational information, not medical advice.

Frequently asked questions

What should I look for first on a nutrition label?

The serving size, then per-100g values to compare. Then energy, saturates, sugars and salt.

What does %RI mean?

Reference intake: the share of an average adult’s guide amount, set out in EU-derived rules used in the UK. Your own needs may differ.

Is sugar on the label added sugar?

On UK labels, “of which sugars” is total sugars—natural and added. US labels show added sugars separately. The ingredients list shows added sugars by name.

Are all UK foods required to show traffic lights?

No. Front-of-pack colour coding is voluntary in the UK. The back-of-pack nutrition declaration is required on most pre-packed foods; see UK government labelling guidance.

Keep learning

Lesson 7: Understanding Food Labels