Compare the portion, not just the label
Imagine two yogurt labels. These are illustrative numbers, not specific products. Yogurt A lists 120 calories and 12 g protein per 150 g. Yogurt B lists 160 calories and 18 g protein per 200 g.
| Food | Calories | Protein |
|---|---|---|
| Yogurt A | 120 × 200 ÷ 150 = 160 | 12 × 200 ÷ 150 = 16 g |
| Yogurt B | 160 | 18 g |
The lower-calorie label did not mean fewer calories for the portion you wanted. At the same weight, the calories match and B has 2 g more protein. Price, taste and ingredients may still change your choice.
Try this comparison with your own labels. Serving sizes on U.S. labels describe amounts people typically consume; they are not a recommendation for how much you should eat. FDA label guidance.
1. Check the serving and the package
A serving size describes an amount people typically consume; it is not advice about how much you should eat. Check servings per container too. Some labels show both a per-serving column and a whole-package column.
If one serving is 40 g and you eat 60 g, multiply the per-serving numbers by 1.5. For example, 160 calories per serving becomes 240 calories in your portion.
2. Read the nutrients you care about
Calories tell you about energy. Protein, fiber, saturated fat, sodium and added sugar help you understand other parts of the food. There is no single line that decides whether a food belongs in your meals.
- Total carbohydrate already includes fiber and sugars. Do not add them again.
- Total fat already includes saturated and trans fat.
- Added sugars are part of total sugars, not an extra amount on top.
- Use protein grams when comparing protein; many labels do not show a protein %DV.
3. Use % Daily Value as a quick guide
The FDA’s rule of thumb is 5% DV or less is low and 20% DV or more is high for a nutrient in one serving. Daily Values are general reference amounts, not your personal targets.
The 2,000-calorie statement provides general nutrition context. It does not mean everyone needs 2,000 calories, or that every Daily Value scales directly with your own calorie intake.
4. Compare the same amount
Two products may use different serving sizes. Comparing equal weights helps when the foods serve a similar purpose. Comparing the portions you actually eat may be more useful for planning a meal.
Our food comparison tool offers per-serving, per-100-g and per-100-calorie views. These answer different questions; none is an overall health score.
5. Check ingredients and allergens
Ingredients are generally listed from greatest to least weight. Their order does not reveal exact percentages, and a long list is not automatically worse than a short one.
Read the allergen statement and ingredient list if you have an allergy. Do not assume that a missing precautionary warning rules out cross-contact.
Why don’t the numbers always add up?
Nutrition labels use rounding rules. Fiber, sugar alcohols and other ingredients can also affect calorie calculations. Small differences between printed calories and a calculation using 4 calories per gram of protein or carbs and 9 per gram of fat are not automatically errors.
Sources
Apply the serving calculation to a real label
The Canadian retailer label for Kirkland Signature Natural Peanut Butter lists 90 kcal, 4 g protein, 4 g carbohydrate and 7 g fat per 15 g. A weighed 30 g portion is two such servings: 180 kcal, 8 g protein, 8 g carbohydrate and 14 g fat. A spoonful is not automatically 15 g; weigh it or use a supported package measure.
This example uses the Canadian supplier-label record; the main U.S. label explanation above still describes U.S. conventions. Do not transfer a Canadian % Daily Value interpretation or product recipe to a U.S. package without checking its own label. A product name or barcode lookup does not independently verify the package in your hand.
Scroll across for the full comparison.
| Food and listed portion | kcal | Protein (g) | Carbs (g) | Fat (g) | Fiber (g) | Sodium (mg) |
|---|---|---|---|---|---|---|
| Kirkland Signature · Natural Peanut Butter Canada · 15 g, calculated from the retailer label | 90 | 4 | 4 | 7 | 1 | 0 |
| Kirkland Signature · Natural Peanut Butter Canada · 30 g, calculated from the retailer label | 180 | 8 | 8 | 14 | 2 | 0 |
Sources and serving limits
- Kirkland Signature · Natural Peanut Butter source · edition date not stated; record checked 2026-10-12.