Comparing Nutrition Labels? Put Both Foods on the Same Basis

Before deciding which packaged food has less sodium or more fiber, check that you are comparing the same amount. A smaller printed number may simply describe a smaller serving. Put both labels on a common basis, then consider the portion you will actually eat.

This is a shopping tool, not a rule that every meal must be weighed. A little arithmetic can settle a comparison that attractive packaging cannot.

Read the top of the label first

Look for serving size and servings per container. On a U.S. Nutrition Facts label, the household measure is followed by an amount in grams or milliliters where appropriate. Nutrient figures usually refer to that listed serving.

FDA explains that serving sizes reflect amounts people typically consume. They are not a recommendation for how much you personally should eat. A package may also contain several servings, even if you usually finish it at once.

Compare like with like

For two similar foods, check whether the listed weights match. If both show 40 grams, you can compare their figures directly. If one uses 30 grams and the other 60 grams, double the smaller serving’s figures to compare both at 60 grams.

Here is an illustrative example, not a real product comparison. Cereal A lists 120 calories and 150 milligrams of sodium per 30 grams. Cereal B lists 220 calories and 240 milligrams of sodium per 60 grams. At 60 grams, A provides 240 calories and 300 milligrams of sodium. B has the lower numbers on that common basis.

Check other nutrients before choosing. One difference does not identify a universally better food. Also remember that rounded label values make calculated results approximate.

Use your likely portion for the meal decision

An equal-weight comparison answers a shopping question. Your actual portion answers a different question: what will this food contribute to your meal?

If you expect to eat two listed servings, multiply the calories and nutrient amounts by two. For a label with separate per-serving and per-package columns, use the column that matches what you intend to eat. Do not accidentally read a per-serving number as the whole package.

For breakfast cereal, the dry-food label does not automatically include milk, yogurt or toppings. Consider those separately. Likewise, compare a concentrated drink and a ready-to-drink version as prepared, following the package directions, rather than comparing unequal forms.

Choose the comparison that matters to you

You do not need to calculate every line in the aisle. Start with one useful question: are you comparing sodium in two soups, added sugars in two drinks or fiber in two cereals?

On U.S. labels, percent Daily Value is another quick comparison aid when the serving amounts are the same. FDA identifies 5 percent or less as low and 20 percent or more as high for a nutrient. These are label reference points, not personalized targets.

If you have a prescribed eating plan, use its guidance rather than treating the label’s general reference values as your instructions.

Finish with a practical choice

Once the amounts match, consider taste, price and how you will use the food. The label can resolve a nutrient comparison; it cannot tell you which purchase you will enjoy or finish. Keep the winning habit simple: check the serving, compare equal amounts and account for your actual portion.

Sources and further reading

• FDA: How to Understand and Use the Nutrition Facts Label — U.S. Food and Drug Administration
• FDA: Serving Size on the Nutrition Facts Label — U.S. Food and Drug Administration