A nutrition label carries a lot more useful information than it looks like at a glance, but it’s easy to misread if you only skim the calorie count. Once you understand how a label is structured, reading one takes just a few seconds.

Start with the serving size

The first thing worth checking is the serving size the entire label is based on. It’s often noticeably smaller than what people actually eat in one sitting — a listed serving of chips or cookies might be a third or a quarter of the bag. If your real portion is twice the listed serving, then calories and every other number on the label need to be roughly doubled in your head, or the numbers will look far lower than what you’re actually eating.

Calories per serving vs. calories per 100 g

Many labels list calories both per serving and per 100 g, and it’s worth keeping those two numbers straight. The per-100-g figure is useful for comparing different products regardless of package size, while the per-serving figure tells you how many calories you’ll actually get in one sitting. When comparing two similar products at the store, the per-100-g number is usually the more reliable one to go by.

Protein, fat, and carbohydrates

Below the calorie count, labels usually break down protein, fat, and carbohydrates per serving, often with subcategories — saturated fat separate from total fat, sugars separate from total carbs. Saturated fat and added sugar are the numbers worth watching most closely when choosing between similar products, while higher protein and fiber are generally the more desirable direction.

Sugar and added sugar are not the same thing

It’s worth distinguishing total sugar from added sugar when a label breaks that out. A product can contain natural sugar — from fruit or milk, for instance — without a gram of added sugar, and conversely, a product that looks “healthy” can be generously sweetened during manufacturing. Added sugar is worth tracking separately, since it’s the form most often linked to extra calories in the diet without much additional nutritional value.

Salt and sodium

Salt or sodium content matters especially for anyone watching their blood pressure or heart health. Processed foods — canned goods, sauces, ready meals, snacks — often contain far more salt than taste alone would suggest, so it makes sense to check the actual number on the label rather than trust how salty something tastes.

The ingredient list: order matters

The ingredient list on a package is always ordered by weight, from most to least. If sugar, syrup, or vegetable oil appears near the top, that’s a sign it makes up a significant share of the product, even if the product name itself sounds fairly neutral. It also helps to know that sugar shows up under many different names on labels — syrup, dextrose, maltodextrin, fruit juice concentrate — and all of them are, functionally, forms of added sugar.

Package claims are worth double-checking

Words like “natural,” “light,” or “sugar-free” are regulated differently depending on the country and don’t always mean what a shopper might assume. “Sugar-free” doesn’t guarantee a low-calorie product if it’s been made up for with fat or sweeteners, and a “light” version of a product sometimes differs only marginally from the regular one. The only reliable way to check these claims is to compare the actual numbers on the label against the regular version of the same product.

The practical takeaway

To size up a product quickly from its label, it’s enough to check three things in order: the real serving size compared to what you’ll actually eat, the calorie and macronutrient numbers per 100 g for comparing against similar products, and the first few items in the ingredient list. That quick check takes under a minute but gives a far more accurate picture of a product than a glance at the front of the package.