Reading a label does not take long once you know where to look. This guide covers the two label styles you are most likely to see: the UK-style traffic lights and the US Nutrition Facts panel.
UK and EU style: traffic lights and “per 100 g”
Many UK packs have a front-of-pack label that uses red, amber and green to show whether a food has high, medium or low amounts of fat, saturated fat, sugars and salt. Red means high, amber medium and green low. The NHS says a product with mostly green is generally a healthier choice, and that you should limit anything with a lot of red.
Per 100 g thresholds
| Nutrient | High (red) | Low (green) |
|---|---|---|
| Total fat | More than 17.5 g | 3 g or less |
| Saturated fat | More than 5 g | 1.5 g or less |
| Sugars | More than 22.5 g | 5 g or less |
| Salt | More than 1.5 g (or 0.6 g sodium) | 0.3 g or less (or 0.1 g sodium) |
Anything between low and high is amber. These per-100 g thresholds make it easy to compare two products, because both are measured for the same weight.
Reference intakes
Many labels also show reference intakes (RIs). These are guidelines for the approximate amount of energy and nutrients needed for a healthy diet. A label might tell you that a portion provides a percentage of an adult’s reference intake.
US style: the Nutrition Facts label
The FDA explains how to use the Nutrition Facts label and the “% Daily Value” (%DV).
- Check the serving size first. The %DV applies to one serving, which the label states at the top. If you eat two servings, double the numbers. For example, 37% DV of sodium in one serving becomes 74% for two.
- Use the 5/20 rule. A %DV of 5% or less per serving is low. A %DV of 20% or more is high.
- Limit saturated fat, sodium and added sugars. Choose foods with a lower %DV for these, and try to keep your daily total below 100% DV. If you eat something high in one, balance it with lower choices later in the day.
- Get more fibre, vitamin D, calcium, iron and potassium. Choose foods with a higher %DV for these.
- Note the exceptions. Total sugars and trans fat do not have a %DV. Total sugars include natural and added sugars, so look at the “Added sugars” line.
A 60-second routine
- Look at the serving size or the per 100 g column.
- Check sugars (and “added sugars” in the US).
- Check saturated fat and salt or sodium.
- Glance at the ingredients. They are listed from most to least, so if sugar or syrup is near the top, there is a lot of it.
- Compare with a similar product and choose the one with lower sugar, saturated fat and salt.
Quick example
Two breakfast cereals are each marked per 100 g. Cereal A shows 3 g of sugars, which is green. Cereal B shows 24 g of sugars, which is red (above 22.5 g). If you eat a 40 g bowl, Cereal B gives you about 10 g of sugar (24 g × 0.4), which is about a third of the NHS’s 30 g adult maximum. That is easier to see on a label than to guess in a shop. For daily limits, see how much sugar per day.
A worked example (made-up product)
Here is a made-up breakfast cereal label, so you can practise.
| Per 100 g | Amount | Traffic light |
|---|---|---|
| Fat | 7 g | Amber (between 3 g and 17.5 g) |
| Saturated fat | 1.2 g | Green (1.5 g or less) |
| Sugars | 24 g | Red (more than 22.5 g) |
| Salt | 0.4 g | Amber (between 0.3 g and 1.5 g) |
The packet says a serving is 30 g. So one serving gives you about 7 g of sugar (24 g × 0.3). If you pour a 60 g bowl, that is about 14 g, roughly 3 to 4 teaspoons, or nearly half of the NHS’s 30 g adult limit for free sugars. The cereal is not “bad”, but the label shows you that the amount you pour matters.
Serving size traps
- A pack may contain more than one serving, so a single bag of snacks can be 2 or 3 servings.
- Serving sizes are set by the manufacturer and may be smaller than what you really eat.
- On a US label, if you eat two servings, you double every number, including the %DV.
Front-of-pack claims
Claims such as “natural”, “wholesome” or “light” are marketing and can mean different things. Turn the pack over and check the numbers and the ingredients list.
Allergens
Allergen information is usually highlighted in the ingredients list, for example in bold. If you have an allergy, read the list every time, because recipes can change.
What labels do not tell you
A label cannot say whether a food is right for you. It does not tell you how much to eat, or replace advice from a doctor or registered dietitian if you have a health condition or allergy. And remember that a food with a good label can still be easy to overeat.
Frequently asked questions
What is the most important number on a label?
It depends on your goal. Most people benefit from watching sugars, saturated fat and salt, as the NHS and FDA suggest, and from looking at fibre.
Should I look per 100 g or per serving?
Per 100 g is best for comparing two products. Per serving is best for working out what you will actually eat.
What does %DV mean?
It tells you how much a serving contributes to a daily diet, based on reference values. The FDA says 5% or less is low and 20% or more is high.
Are “reference intakes” a target?
No. They are guidelines for the approximate amounts of energy and nutrients needed for a healthy diet. Your needs vary.
To see how a label fits your own day, find your calories and sugar limit with our calorie calculator.