How to Read UK Nutrition Labels (Traffic Lights Explained)

UK packaging carries two kinds of nutrition information: the full table, usually on the back, and the colour-coded traffic lights some brands put on the front. Here’s how to read both.

The back-of-pack table

Pre-packed food must show energy (in kJ and kcal), fat, saturates, carbohydrate, sugars, protein and salt, per 100 g or 100 ml. Many products add a per-portion column too. Fibre is often included but isn’t mandatory.

Use the per-100g column to compare products fairly, and the per-portion column (or our portion calculator) to see what you’ll actually eat — after checking that the manufacturer’s portion matches yours.

kJ and kcal

Energy is shown in kilojoules and kilocalories. What most people call “calories” are kilocalories. To convert, divide kJ by 4.184.

Salt, not sodium

UK labels show salt. If you see sodium (common on imported food), multiply by 2.5 to get salt. Adults are advised to have no more than 6 g of salt a day.

Traffic lights

Front-of-pack labels are voluntary, but when used they follow government criteria. For foods, the colours are based on amounts per 100 g:

Per 100 g (food)	Green (low)	Amber (medium)	Red (high)
Fat	3 g or less	3–17.5 g	more than 17.5 g
Saturates	1.5 g or less	1.5–5 g	more than 5 g
Sugars	5 g or less	5–22.5 g	more than 22.5 g
Salt	0.3 g or less	0.3–1.5 g	more than 1.5 g

Reference intakes (%RI)

Percentages on the front of packs compare the portion to reference intakes for an average adult. They’re a yardstick for labels, not personal targets.

Nutrient	Reference intake
Energy	8,400 kJ / 2,000 kcal
Fat	70 g
Saturates	20 g
Carbohydrate	260 g
Sugars	90 g
Protein	50 g
Salt	6 g

A two-minute habit

When choosing between similar products, compare the per-100g column for the thing you care about most — energy, protein, saturates or salt. A label scan in the app does this for you and checks whether the numbers add up.

This guide is general information, not medical advice.

How to read UK nutrition labels