How to Read a Nutrition Label for Calories

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Disclaimer: This article is general nutrition information, not medical advice. Every calorie figure here is an estimate. If you have a medical condition or specific dietary needs, talk to a doctor or registered dietitian.

When you read a nutrition label for calorie counting, the number to copy is the gram weight in parentheses, not the cup. The calories and nutrients on the panel all describe that weight. With it and a kitchen scale, you can turn any label into the portion you actually ate.

This guide works through one label, FDA’s own sample panel for frozen lasagna, from the serving line down to the footnote. For food with no label at all, how to calorie count homemade food covers the batch method.

Log the grams. “1 cup” is a convenience. The (227g) after it is what the numbers describe.
Scale through per 100 g. Calories ÷ serving grams × 100 gives a figure you can compare across brands and multiply by any portion.
Copy the printed calories. They’re rounded, and the macros won’t multiply out exactly. That’s normal.
%DV isn’t a calorie tool. It’s pinned to a fixed 2,000-calorie reference and doesn’t move with your target.

Start with the grams, not the cup

On most US Nutrition Facts labels, the serving size is a household measure followed by the metric amount in parentheses: grams for foods, milliliters for drinks. Log the number in parentheses.

FDA’s sample lasagna reads “1 cup (227g).” The cup tells you roughly how much to scoop. The 227 g is the weight the calories and macros describe, and it’s what your scale reads.

A label “cup” is a cup of that particular food, so it carries its own weight. FDA’s rules also fix some labeling equivalents: “a cup means 240 mL” and “1 oz in weight means 28 g,” among others. That’s why a 1 oz serving prints as 28 g rather than 28.35. Use the label’s own gram figure and don’t re-convert the ounces yourself.

The serving size isn’t advice on how much to eat. In FDA’s words, “The serving size reflects the amount that people typically eat or drink. It is not a recommendation of how much you should eat or drink.” The 2016 update changed some of the reference amounts that servings are based on. Ice cream’s went from 1/2 cup to 2/3 cup and soda’s from 8 ounces to 12, while yogurt’s dropped from 8 ounces to 6.

“About 2.5 servings” is a rounded number

Servings per container is rounded. Counts go to the nearest whole number, except that counts between 2 and 5 go to the nearest 0.5. The regulation says the word “about” signals the rounding, as in “about 2 servings, about 3.5 servings.”

So “about 2.5 servings” times the per-serving calories isn’t exact. If you eat the whole package, look for a per-package column first. If there isn’t one and the package lists its net weight in grams, multiply the calories per gram by that weight instead.

One serving, two columns or the whole package

Two rules decide whether the numbers already cover the whole thing:

Single-serving packages. A package holding less than 200% of the food’s reference amount must be labeled as one serving. FDA’s examples are a 20-ounce soda and a 15-ounce can of soup, “because people typically consume it in one sitting.”
Dual-column labels. A package holding 200% to 300% of the reference amount usually gets a second column for the entire package, next to the per-serving one. The exceptions include raw produce, seafood and mixes that already carry an “as prepared” column. A 24-ounce bottle of soda and a pint of ice cream are the examples FDA gives.

Finish a dual-column package and you copy the per-package column. There’s nothing to multiply.

Dry, prepared or drained

Label values describe the food “as packaged or purchased.” Dry pasta, rice and oats are sold dry, so their panels describe the dry food. Weigh them dry before cooking, or convert a cooked weight with the raw to cooked weight calculator.

Some packages add a second “as prepared” column, such as a mix with directions to add milk or eggs, but it’s optional. Food packed in a liquid you don’t usually eat (canned fish, maraschino cherries, pickled fruits and vegetables) is labeled on the drained solids, so drain it before you weigh.

Turn the label into your portion

FDA’s sample lasagna isn’t a real product, but it reads like one: 1 cup (227 g) per serving, 280 calories, 15 g of protein, 34 g of carbohydrate and 9 g of fat, with 4 servings in the package.

If you eat more than one serving, FDA says to multiply. Two cups means “two times the calories and nutrients shown,” %DVs included. That works for whole servings, but a scale rarely lands on one, so go through grams:

Per gram: label calories ÷ serving grams. 280 ÷ 227 = 1.233 kcal per gram.
Per 100 g: multiply by 100, for 123.3 kcal per 100 g.
Your portion: grams weighed × per-100 g figure ÷ 100. A 300 g plate is 300 × 123.3 ÷ 100, or about 370 kcal.

Do the same for each macro:

Nutrient	Label serving (1 cup, 227 g)	Per 100 g	A 300 g plate
Calories	280	123.3	370
Protein	15 g	6.6 g	19.8 g
Carbs	34 g	15.0 g	44.9 g
Fat	9 g	4.0 g	11.9 g

Eat the whole package and FDA’s own figure is 4 servings, or 1,120 calories. The food calories by weight calculator does this scaling from either a per-serving or a per-100 g label.

Why per 100 g is worth knowing

Serving sizes differ from brand to brand, so two products’ per-serving calories don’t compare directly. Put both on a per-100 g basis and the denser one is obvious.

US labels may add a per-100 g (or per-100 mL) column, but it’s optional. In the UK it’s standard: the UK’s retained version of Regulation (EU) No 1169/2011 says the energy value and nutrients “shall be expressed per 100 g or per 100 ml.” If you shop in both countries, per 100 g is the common language.

Watch the carbohydrate line when you copy a UK label. There it means carbohydrate “which is metabolised by humans,” and fibre gets its own line. A US “Total Carbohydrate” is calculated by difference, so it includes fiber. Don’t subtract fibre from a UK carbohydrate figure, because it was never in there.

Labels in kilojoules

A US label may also list kilojoules in parentheses after the calories. FAO gives the conversion as “1 kcal = 4.184 kJ,” so divide kJ by 4.184: 1,000 kJ is about 239 kcal.

What the calorie number counts

FDA defines label calories as the energy “from all sources (carbohydrate, fat, protein, and alcohol)” in a serving. The common method uses 4 calories per gram for protein and carbohydrate and 9 for fat, the general factors from USDA’s Agriculture Handbook No. 74. Some labels print them at the bottom: “Calories per gram: fat 9, carbohydrate 4, protein 4.”

It isn’t the only method the regulation allows. A manufacturer may also:

Use food-specific factors instead of the general ones.
Subtract non-digestible carbs and sugar alcohols before applying 4/4/9, counting soluble non-digestible carbs at 2 calories per gram.
Use listed factors for sugar alcohols, such as 2.4 calories per gram for xylitol and 0 for erythritol.
Burn the food in a bomb calorimeter and subtract 1.25 calories per gram of protein for incomplete digestion.

Check the macros against the calories

The factors are applied to the actual amounts, before rounding. Then calories are rounded to the nearest 5 up to 50 calories and to the nearest 10 above that, while fat, carbs and protein are rounded on their own.

So 4/4/9 on the printed grams is only a rough check. For the lasagna, 15 × 4 + 34 × 4 + 9 × 9 = 277, and the label says 280. When the two disagree, copy the printed calories. The macros to calories calculator runs this check for any label. A bigger gap on a high-fiber or sugar-free product can mean the maker used one of the other methods above.

The printed calories have slack of their own, too: FDA treats a food as misbranded when its calories run more than 20% above the label.

When zero isn’t zero

A serving with less than 5 calories may be labeled as 0, and fat below 0.5 g per serving is declared as 0 g. Cooking spray shows how this plays out. FDA’s reference amount for spray oils is 0.25 g, stated on the label as about so many seconds of spray.

If that 0.25 g were all oil at 9 calories per gram, it would come to about 2.25 kcal (our arithmetic, not a label figure). That’s under 5, so the panel can say 0. A long spray is several servings, each rounded to nothing, so log what you actually use. FDA also points out that “fat-free” and “no added sugars” don’t mean “calorie-free.”

Alcohol

Alcohol counts toward calories but has no gram line of its own on the panel. FAO lists a general factor of “29 kJ/g [7.0 kcal/g]” for it. Alcohol macros covers how to log a drink’s alcohol calories.

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What % Daily Value does and doesn’t tell you

The %DV column shows how much of a fixed Daily Value one serving supplies. The label’s footnote spells it out: “The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.” The column doesn’t add up to 100%, because each line is measured against its own Daily Value.

FDA’s rule of thumb is that 5% DV or less per serving is low and 20% DV or more is high. That’s useful for sodium, fiber, saturated fat and added sugars. It doesn’t help with calories, which get no %DV: the regulation’s table of Daily Reference Values has no entry for energy.

Protein usually has no %DV either. It’s required only when the label makes a protein claim or the food is meant for infants or children 1 through 3 years old. For protein, FDA says to “use the number of grams (g) as a guide.”

The Daily Values don’t move with your target

For adults and children 4 and older, the Daily Values are fixed at the 2,000-calorie reference: 78 g of fat, 275 g of total carbohydrate and 50 g of protein. Your own target may differ. FDA’s page says calorie needs “may be higher or lower and vary depending on your age, sex, height, weight, and physical activity level.”

Even at 2,000 calories, a macro split changes the picture. A split of 30% protein, 40% carbs and 30% fat works out to 150 g of protein, 200 g of carbs and about 66.7 g of fat. Here’s one serving of the lasagna both ways:

Per serving	Amount	Label %DV	Share of a 2,000-calorie 30/40/30 target
Fat	9 g	12%	13.5% of 66.7 g
Carbs	34 g	12%	17% of 200 g
Protein	15 g	None printed (30% of the 50 g DV)	10% of 150 g

The label makes the lasagna look equally modest on fat and carbs, and says nothing on protein. Against this target it’s a bigger share of your carbs and a much smaller share of your protein than the DVs suggest. Log the grams and measure them against your own targets. Carb protein fat ratio shows how to turn any split into grams.

If you learned to read labels before the 2016 update, one line is gone. “Calories from Fat” was removed because, in FDA’s words, “research shows the type of fat is more important than the amount.” Manufacturers had until January 1, 2020 or January 1, 2021, depending on their annual food sales, to switch.

Save the label once as a custom food

Most of the work in label reading is transcription, so do it once. Save the packaged food in your tracker in the label’s own units, then log it by weight after that.

Counter44, the calorie and macro tracker behind this site, has no barcode scanner and no online food search, so a packaged food goes in by hand. Its built-in foods are about 7,200 entries derived from USDA data, stored per 100 g or mL, and your package may not match any of them. For a specific product, the label in your hand is the better source.

Here’s the lasagna as a custom food:

Create it. On Add food, type the product name and tap the last row, Create custom, which opens New food with the name filled in. To save a food without logging it, use My foods, then New food.
Set the serving. Serving size is the label’s grams (227 g). Serving label is the household measure (“1 cup”).
Enter the label as printed. Switch to the per-serving chip (it reads Per 1 cup once the label is set) and type 280 calories, 15 g protein, 34 g carbs and 9 g fat. The fields take one decimal.
Log what you weighed. From Create custom, the Portion sheet opens at one serving after you save. Pick the g chip and step to the weight on your scale, 5 g per tap (holding speeds up), or use the 1 cup chip in half-serving steps. Portions are always grams or mL, even with Imperial units.
Next time, tap once. On Add food, the food’s Recents chip repeats your last portion, and once it drops out of Recents, its Your foods chip logs one serving. To log a different weight, search for the food and step it in Portion.

Food logging, custom foods and Quick add are free, with no account and no ads.

There are two catches. New food stores only calories, protein, carbs and fat, so fiber, sugars and sodium stay on the package. And each entry keeps its own copy of the numbers, so editing the food later doesn’t change meals you’ve already logged. For a one-off you won’t eat again, Quick add takes the calories plus whole-gram protein, carbs and fat directly.

References

eCFR. 21 CFR 101.9, Nutrition labeling of food. Serving size in household and metric units, labeling equivalents, servings-per-container rounding, single-serving and dual-column rules, the as-packaged and drained-solids basis, optional per-100 g and as-prepared columns, calorie methods and rounding, zero rules, Daily Reference Values, the %DV footnote and the 20% misbranding threshold.
eCFR. 21 CFR 101.12, Reference amounts customarily consumed per eating occasion. Spray-type fats and oils: 0.25 g, stated as about so many seconds of spray.
U.S. Food and Drug Administration. How to Understand and Use the Nutrition Facts Label. The sample lasagna label (280 calories per serving, 4 servings, 1,120 calories per package), serving sizes as typical amounts, 5% low and 20% high, and protein %DV.
U.S. Food and Drug Administration. Serving Size on the Nutrition Facts Label. The sample lasagna serving: 1 cup (227g).
U.S. Food and Drug Administration. Calories on the Nutrition Facts Label. Calories from carbohydrate, fat, protein and alcohol; “fat-free” and “no added sugars” don’t mean “calorie-free.”
U.S. Food and Drug Administration. The Lows and Highs of Percent Daily Value on the Nutrition Facts Label. Protein generally has no %DV; use the grams.
U.S. Food and Drug Administration. Changes to the Nutrition Facts Label. The 2016 update: updated reference amounts, single-serving and dual-column examples, removal of Calories from Fat, and compliance dates.
Federal Register. Food Labeling: Revision of the Nutrition and Supplement Facts Labels, 81 FR 33742, May 27, 2016. The final rule behind the 2016 label.
Merrill, A. L. and Watt, B. K. Energy Value of Foods: Basis and Derivation. USDA Agriculture Handbook No. 74. Source of the general 4, 9 and 4 calorie factors.
FAO. Food energy: methods of analysis and conversion factors. FAO Food and Nutrition Paper 77, Chapter 3. General factor for alcohol (7.0 kcal/g) and the kJ to kcal conversion.
legislation.gov.uk. Regulation (EU) No 1169/2011 as retained in UK law, Article 32. Energy and nutrients expressed per 100 g or per 100 ml.
legislation.gov.uk. Regulation (EU) No 1169/2011 as retained in UK law, Annex I. Definitions of carbohydrate and fibre.

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Frequently Asked Questions

Should I log a packaged food by the serving size or by grams?

By grams. A US label gives the serving as a household measure followed by the metric amount in parentheses, such as 1 cup (227g), and the numbers on the panel describe that weight. Weigh your portion and scale the label to it.

How do I convert a nutrition label to calories per 100 g?

Divide the calories by the serving's grams, then multiply by 100. FDA's sample lasagna label works out to 280 ÷ 227 × 100 = 123.3 kcal per 100 g. Do the same for protein, carbs and fat. For your portion, multiply the per-100 g figure by the grams you ate and divide by 100.

Are the calories on a nutrition label for one serving or the whole package?

One serving, unless the package counts as a single serving (less than 200% of the food's reference amount) or the label adds a per-package column (packages at 200% to 300%). Servings per container is rounded: 'about' in front of the number means it was rounded, and counts between 2 and 5 go to the nearest 0.5.

Why does a label say 0 calories when the food has some?

US rules let a serving with less than 5 calories be labeled as 0, and fat below 0.5 g per serving is declared as 0 g. The reference amount for spray oils is 0.25 g, which at 9 calories per gram is about 2.25 kcal, so one labeled spray can read 0. Log what you actually use.

Why don't the protein, carbs and fat add up to the calories?

Calories are calculated from the unrounded amounts and then rounded to the nearest 5 or 10, while the grams are rounded on their own. Manufacturers may also subtract non-digestible carbs and sugar alcohols or use other approved methods. 4/4/9 on the printed grams is a rough check: FDA's sample lasagna gives 277 against a printed 280.

Does the % Daily Value tell me how many calories to eat?

No. %DV is each nutrient's share of a fixed Daily Value based on a 2,000-calorie reference, and calories have no %DV at all. The Daily Values (78 g fat, 275 g carbs, 50 g protein) stay the same whatever your own target is, so log the grams instead.

Is the nutrition label for the food dry or cooked?

As packaged or purchased, unless the label has a second 'as prepared' column. Dry pasta, rice and oats are sold dry, so their panels describe the dry food. Weigh them dry, or convert a cooked weight before you log it.

How do I log a packaged food that isn't in Counter44's food list?

Create a custom food once. Set Serving size to the label's grams and Serving label to the household measure, switch to the per-serving chip and enter the label's calories, protein, carbs and fat. After that, log the grams you weighed. Counter44 has no barcode scanner or online food search, so the label is typed in once and then reused from Your foods and Recents.