how to read food labels
How to Read Food Labels Without Overthinking It
A plain-English guide to nutrition labels, serving sizes, per-100g comparisons and traffic lights.
Reviewed 15 July 2026. Sources: NHS and USDA FoodData Central.
Quick answer
Use the per-100g column to compare similar packaged foods, then check the serving size to see what you are likely to eat. Start with salt, saturated fat, sugar and fibre when those are relevant to your choice.
Per 100g is your fair comparison
Serving sizes on packs can be useful, but they are set by the manufacturer and may not match your portion. Per 100g lets you compare two cereals, sauces or ready meals on the same basis.
You do not need to compare every number every time. Pick one or two that matter for the food in front of you. For bread, salt and fibre might be useful. For yoghurt, sugar and protein may help.
Use traffic lights as a quick signal
Front-of-pack traffic lights can show whether a food is high, medium or low in fat, saturated fat, sugars and salt. More green and amber can be a useful shortcut when you are choosing between similar options.
A red light is not a ban. It tells you that the food is high in that nutrient, which can help you decide how often or how much to have.
Keep the ingredient list in the picture
The nutrition panel gives numbers, while the ingredients list tells you what made them. Both can be useful if you have an allergy, preference or a goal such as eating more wholegrains.
Avoid spending an hour finding the perfect product. A comparison that helps you buy food you will actually eat is enough.
Questions people ask
Should I use calories or per 100g?
They answer different questions. Per 100g is best for comparing similar products. Energy per serving can help you understand the portion you plan to eat.
Are traffic lights reliable?
They are a helpful starting point, especially for comparing similar foods. Use the full label when you need more detail.
Sources and notes
This guide is for general nutrition information. It does not diagnose a deficiency, treat a condition or replace personal medical advice.
- NHS: Food labels
Using labels to compare foods
- NHS: Reduce salt
Salt limits and label guidance
- NHS: Sugar: the facts
Free sugars and practical swaps