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Key takeaways
- Start with serving size. Every number on the label is for one serving, and packages often hold two or three.1
- The 5 and 20 rule: 5 percent Daily Value or less is low, 20 percent or more is high. Use it for both the nutrients you want less of and the ones you want more of.1
- Limit saturated fat, sodium and added sugars. Get more dietary fiber, vitamin D, calcium, iron and potassium.1
- Added sugars has its own line on US labels. Total sugars includes the natural sugar in milk and fruit; added sugars is the part that was put in.3
- Labels are not exact. US rules allow calories, sugars, fat and sodium to run up to 20 percent above the declared value and still comply.6
The 60-second order
- Serving size and servings per container. Decide how many servings you will really eat.
- Calories per serving, multiplied by that number.
- Saturated fat, sodium, added sugars: aim for 5 percent Daily Value or less per serving, and treat 20 percent or more as a reason to pause.
- Dietary fiber, vitamin D, calcium, iron, potassium: here 20 percent or more is the goal.
- The first three ingredients, and any sugar hiding under another name.
1. Serving size
Serving sizes on US labels are based on the amount people typically eat in one sitting, not on what anyone recommends. They were updated in 2016 to reflect real habits, which is why a bottle of soda is now often one serving rather than two and a half. Packages that could be eaten in one go but contain two or three servings may carry a dual-column label showing both per-serving and per-package figures.1
The trap is the bag of chips, the pint of ice cream or the bottle of juice where "serving" and "what I ate" differ by two or three times. Multiply before you judge.
2. Calories
Calories are printed large because they are the first thing most people want. The label's percent values are built around a 2,000-calorie day, which the FDA uses as a general reference; your own needs may be higher or lower (see how many calories you should eat).1
3. Lines to limit
The FDA singles out three nutrients Americans generally eat too much of: saturated fat, sodium and added sugars. Their Daily Values, the reference amounts behind the percentages, are 20 g, 2,300 mg and 50 g respectively.2 Five percent of the Daily Value or less per serving is considered low; 20 percent or more is high.1
| Nutrient | Daily Value | Low (5% DV or less) | High (20% DV or more) |
|---|---|---|---|
| Saturated fat | 20 g | 1 g or less | 4 g or more |
| Sodium | 2,300 mg | 115 mg or less | 460 mg or more |
| Added sugars | 50 g | 2.5 g or less | 10 g or more |
Trans fat is listed too, without a percent. Since 2018 partially hydrogenated oils, the main industrial source, are no longer permitted in US foods, and a "0 g" declaration is allowed when a serving contains less than 0.5 g.6
4. Lines to get more of
Dietary fiber, vitamin D, calcium, iron and potassium are on the label because most people fall short of them. Daily Values are 28 g of fiber, 20 mcg of vitamin D, 1,300 mg of calcium, 18 mg of iron and 4,700 mg of potassium.2 For these, flip the rule: 20 percent or more per serving is a genuinely good source.
Protein shows grams but usually no percentage, because the FDA only requires a percent Daily Value for protein when a claim is made or the food is for children under four. The reference is 50 g.2
5. The ingredient list
Ingredients are listed in descending order by weight, so the first three tell you what the food mostly is.1 A "whole grain" bread whose first ingredient is enriched wheat flour is mostly refined flour. Sugar can appear under many names: cane sugar, brown sugar, corn syrup, high-fructose corn syrup, dextrose, fructose, glucose, maltose, sucrose, honey, maple syrup, agave nectar, molasses, fruit juice concentrate and malt syrup are all added sugars on the label.3
UK and EU labels
Labels in the UK and EU are built differently. Nutrition values are mandatory per 100 g or 100 ml, which makes products directly comparable regardless of serving size, with per-portion values optional. The reference intakes behind the percentages are 2,000 kcal, 70 g fat, 20 g saturates, 260 g carbohydrate, 90 g sugars, 50 g protein and 6 g salt.5
Many UK products add a front-of-pack traffic-light panel. Per 100 g, fat is red above 17.5 g and green at 3 g or less; saturates red above 5 g and green at 1.5 g or less; sugars red above 22.5 g and green at 5 g or less; salt red above 1.5 g and green at 0.3 g or less. More greens and ambers than reds is the quick test.4 Note that the UK panel shows total sugars rather than added sugars, and salt rather than sodium (salt is sodium times 2.5).
How accurate labels are
The numbers are honest averages, not measurements of the item in your hand. US compliance rules allow calories, sugars, total fat, saturated fat, cholesterol and sodium to be up to 20 percent higher than declared, and vitamins, minerals, fiber and protein to be up to 20 percent lower, before a label is considered out of compliance.6 Rounding adds more slack: calories are rounded to the nearest 5 below 50 and nearest 10 above, and anything under 5 calories can be listed as zero.
For tracking, this means a label value is a good estimate, not a truth. Consistency across days matters more than the last 10 percent on any one item.
Common traps
- "Per serving" on a single-serve-looking package. Check servings per container every time.
- "No added sugar" is not low sugar. Juice, smoothies and dried fruit can carry 20 g or more of natural sugar per serving.
- "Reduced" or "light" is relative. It means 25 percent less than the regular version, which may still be high. "Light" can also refer to color or texture.
- "Natural" has no formal regulatory definition in the United States and says nothing about calories, sugar or sodium.
- "Multigrain" is not "whole grain". Look for "whole" as the first word of the first ingredient.
- Sodium hides in sweet foods. Bread, cereal and baked goods are among the top sodium sources, so check that line even when the food is not salty.
Questions people ask
What does percent Daily Value mean?
It is the share of the daily reference amount for that nutrient contained in one serving, based on a 2,000-calorie day. Five percent or less is low, 20 percent or more is high. The rule works in both directions: low is what you want for sodium or added sugars, high is what you want for fiber or calcium.1
Is total sugars the same as added sugars?
No. Total sugars includes sugars that occur naturally in milk and fruit plus anything added. Added sugars is only the part put in during processing, including syrups, honey and juice concentrates used as sweeteners. The added sugars line has its own Daily Value of 50 g.2, 3
Why does a label say 0 g trans fat when the ingredients list hydrogenated oil?
US rules allow trans fat to be declared as 0 g when a serving contains less than 0.5 g. Fully hydrogenated oils contain almost no trans fat, and partially hydrogenated oils have not been permitted in US foods since 2018, so the ingredient is now rare.6
How accurate are the calories on a food label?
Within about 20 percent. US regulations treat a label as compliant as long as measured calories do not exceed the declared value by more than 20 percent, and rounding rules add a little more tolerance on top.6
What is the difference between US and UK food labels?
US labels are per serving and list added sugars and sodium in milligrams. UK and EU labels are per 100 g, list total sugars and salt in grams, and many UK products add a red, amber and green traffic-light panel using fixed thresholds per 100 g.4, 5
How Calobook uses this
Point Calobook at a nutrition label and it reads the panel exactly as printed, serving size included, so you do not have to type a thing. Scan a barcode and the values come from the fatsecret and Open Food Facts databases instead. Either way you can tap any number to correct it before saving, set how many servings you ate, and see added sugar and sodium counted against your own daily guardrails rather than a generic 2,000-calorie day.
Barcode, nutrition panel or photo: Calobook turns it into calories, macros, fiber, sugar and sodium against targets built for you.
Sources
- US Food and Drug Administration. How to Understand and Use the Nutrition Facts Label
- US Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts Labels
- US Food and Drug Administration. Added Sugars on the Nutrition Facts Label
- NHS. How to read food labels
- European Union. Regulation (EU) No 1169/2011 on the provision of food information to consumers Annex XIII, Reference intakes.
- US Code of Federal Regulations. 21 CFR 101.9, Nutrition labeling of food Paragraphs (c) on rounding and (g) on compliance.
This article is general nutrition information written by the Calobook team from the sources listed above. It is not medical advice and does not replace a consultation with a doctor or registered dietitian. If you are pregnant, breastfeeding, under 18, or managing a medical condition, talk to a professional before changing your diet. Last reviewed October 17, 2026.