Portion Size vs Serving Size: What the Label Means

A portion is the amount of food you choose to eat at one time. A serving is the amount printed on a product's Nutrition Facts label, and all the nutrient amounts on that label, including the calories, refer to that amount. Your portion may or may not match the serving size. The definitions come from NIDDK: Food Portions: Choosing Just Enough for You, which also gives the arithmetic: if one serving has 280 calories and your portion is two servings, you have eaten 280 × 2 = 560 calories.

What is the difference between a portion and a serving?

A portion is a choice: how much food you eat at one time, whether in a restaurant, from a package or at home. A serving is the amount listed on the product's label. Different products have different serving sizes, measured in cups, ounces, grams, pieces, slices or numbers such as three crackers.

The label serving is not advice about how much to eat. By law, serving sizes must be based on the amount of food people typically consume, rather than how much they should consume, according to FDA: Serving Size on the Nutrition Facts Label. The same page states that the serving size is not a recommendation of how much to eat or drink.

MedlinePlus: Portion size uses the word in another way: a "recommended serving size" is the amount of each food you are supposed to eat during a meal or snack, and a portion is the amount you actually eat. On a package, "serving" means the amount people typically eat or drink, not a target.

How do you read serving size and servings per container on the label?

The serving size and the number of servings per container are at the top of the label, with "Servings per container" listed right above "Serving size". The serving size is shown as a common household measure such as a cup, tablespoon, piece or slice, followed by the metric amount in grams. On the FDA's sample frozen lasagna label, one serving is 1 cup (227g) and the container holds four servings.

Six checks turn the label into the number you actually ate:

1. Find "Servings per container". One package of food may contain more than one serving, and the label's calorie figure refers to one serving.
2. Find "Serving size" and note its unit: cups, pieces, slices or grams.
3. Measure or estimate your own portion in that same unit.
4. Divide your portion by the serving size. The result is the number of servings you ate.
5. Multiply the calories, each nutrient amount and each % Daily Value by that number.
6. Check whether the label has two columns. If it does, the second column already shows the totals for the whole package.

The % Daily Value column scales the same way as the calories. The same FDA page counts 5% DV or less of a nutrient per serving as low and 20% DV or more as high, so the lasagna's 37% for sodium is already high at one cup. A two-cup portion carries 74% DV for sodium.

The label footnote uses 2,000 calories a day as a general guide for nutrition advice. Against that guide, the whole lasagna package is 1,120 ÷ 2,000 = 56% of a day's calories. Your own needs may be higher or lower depending on your age, sex, height, weight and physical activity level.

Why did some serving sizes on labels change?

The reference amounts used in 1993, when the Nutrition Facts label was created, were based primarily on food consumption surveys conducted in 1977-1978 and 1987-1988, and the updated ones use 2003 to 2008 data from the National Health and Nutrition Examination Surveys, as FDA: Food Serving Sizes Have a Reality Check explains. Under the update, a serving of ice cream went from half a cup to two-thirds of a cup, while yogurt, which used to come in 8-ounce containers, now has a 6-ounce reference amount.

The FDA also changed the criteria for labeling based on package size. A 20-ounce can of soda and a 15-ounce can of soup are now labeled as one serving, because people are more likely to eat or drink the entire container in one sitting. A package holding at least two and no more than three times the reference amount, such as a 19-ounce can of soup or a 3-ounce bag of chips, must now be labeled both per serving and per package.

For a package with more than three servings, the dual column is not required. Manufacturers only have to label these products per serving, and the FDA's examples are a "party size" bag of chips or a two-liter bottle of soda.

How much do bigger portions add in calories?

This site hosts two archived quizzes, Portion Distortion I (2003) and Portion Distortion II (2004), which ask how food portions have changed in 20 years. The figures below are copied exactly from the archived Portion Distortion quizzes. They are archived figures, not current data, and the column labels "20 Years Ago" and "Today" are the quizzes' own wording.

In the archived French fries figures, the portion grew from 2.4 to 6.9 ounces, which is 6.9 ÷ 2.4 = about 2.9 times the weight, and the calories grew from 210 to 610, which is 610 ÷ 210 = about 2.9 times. The soda went from 6.5 to 20 ounces, 20 ÷ 6.5 = about 3.1 times the volume, for 250 ÷ 85 = about 2.9 times the calories. A 10-question version with the answers on the back is archived as AIM for a Healthy Weight - Portion Distortion Quiz. Its answers describe a 5-ounce muffin where the quiz above lists 4 ounces.

For eating out, the MedlinePlus portion page estimates that a small hamburger instead of a large one saves about 150 calories, a small order of fries about 300 and a small soda 150. Added up, that is 150 + 300 + 150 = 600 calories, and 600 ÷ 2,000 = 30% of the 2,000-calorie label guide.

In the sample one-day food tracker on the NIDDK page, five medium-sized chocolate-chip cookies, logged as "Not hungry/bored", come to 345 calories, or 345 ÷ 5 = 69 calories per cookie. That day's total reached 2,916 calories, which the page describes as more than most people need.

How can you estimate a portion without measuring?

MedlinePlus suggests using your hand and other everyday objects to measure portion sizes, and lists these comparisons:

• One serving of meat or poultry is the palm of your hand or a deck of cards.
• One 3-ounce (84 grams) serving of fish is a checkbook.
• One half cup (80 grams) of cooked rice or pasta is a rounded handful, or a tennis ball.
• Two tablespoons (32 grams) of peanut butter is a ping-pong ball.
• One serving of cheese is a pair of dice.

The same list compares one half cup of ice cream to a tennis ball, while the label serving for ice cream is now two-thirds of a cup. A tennis ball of ice cream is (1/2) ÷ (2/3) = three-quarters of the label serving.

You do not have to measure forever. NIDDK suggests doing it only long enough to learn typical serving and portion sizes, and taking one serving according to the food label and eating it off a plate instead of straight out of the box or bag. It also advises eating slowly, because the brain may take at least 15 minutes to register a full stomach. This site's page Keep an Eye on Portion Size, from the archived Portion Distortion pages, opens with the question "What is the difference between Portions and Servings?"

For eating out, NIDDK suggests sharing a meal with a friend or taking half your meal home. It also suggests looking for calorie information next to food and drink items on menus and menu boards, to understand how many calories are in a standard restaurant portion.

Where do portions fit in a healthy weight?

To achieve or maintain a healthy body weight, the FDA label guidance says to balance the calories you eat and drink with the calories your body uses. The same page adds that the number of servings you consume determines the number of calories you actually eat. The servings per container and the calories per serving are the two label figures that let you calculate that number.

A healthy weight for adults is generally a body mass index between 18.5 and 24.9, according to NHLBI: Aim for a Healthy Weight, which also says to talk to your healthcare provider about what your BMI means for you. This site's BMI Calculator takes a height and weight in U.S. or metric units.

This guide is general education, not a personal eating plan. People with diabetes who count carbohydrates with an exchange list should note MedlinePlus's caution that a "serving" on that list will not always be the same as the recommended serving size. The archived Aim for a Healthy Weight Patient Booklet includes portion and serving size information, sample reduced calorie menus and tips on dining out. This guide is part of the Healthy weight topic on this site.