What Is Serving Size?

Learn what is a serving size and what is a portion size to eat the right amount

Nutrition facts label
The Nutrition Facts label is less accurate than you might expect. Tom Grill/Photographers Choice RF/Getty Images

Serving size is the amount of food that is generally consumed by one person during a single eating occasion. The U.S. Food and Drug Administration provides guidelines to food manufacturers for calculating correct serving size. But healthy eaters should use different serving size guidelines to decide how much food to eat to reach and maintain a healthy weight.

What Is FDA Serving Size?

Many healthy eaters assume that the serving size listed on the Nutrition Facts label is the amount of food that they are supposed to eat.

But that assumption is wrong. The serving size listed on food packages is not the recommended serving. And that’s the law.

According to the Nutrition Labeling and Education Act (NLEA) serving size must be based on the amount of food we typically eat, not on the amount of food we should eat. So how do food manufacturers know how much of their product we typically eat? They are required to use a standard guideline called the Reference Amount Customarily Consumed (RACC) to calculate serving size.

Reference amounts (RACCs) were developed by the Food and Drug Administration (FDA) after years of studying eating behavior. But as you might imagine, the amount of food we typically eat has changed over time. In many cases, we are eating larger portions of popular foods, like bagels and soft drinks. So the way that the FDA determines what is a serving size can change as well.

Serving Size Definitions

If you're trying to eat a healthy diet or if you’re trying to slim down, it’s helpful to understand the difference between these different serving size definitions:

  • Serving size. The amount of food typically consumed during a single eating occasion, based on the FDA’s RACC. Serving size is listed on the Nutrition Facts label.
  • Recommended serving size.  The amount of each food that you should eat as determined by various health organizations.
  • Portion size. The amount of each food that you actually eat.

    So which definition should you use to determine how much food to eat? You can use recommended serving size to guide your decisions. But it's generally best to get personalized recommendations for the amount of food to eat each day. If you learn how to eat correct portions for weight loss, you'll be more likely to reach and maintain a healthy weight.

    What Is a Serving of...

    So what are the most commonly recommended serving sizes of various foods? Guidelines vary, but in general,

    • a serving size of fruit is usually 1 medium whole fruit or ½ cup cooked, canned or dried fruit
    • a serving size of vegetables is usually one cup of raw or cooked leafy greens or ½ cup of higher calorie vegetables like carrots.
    • a serving size of potatoes, pasta or grains is ½ cup  or one slice of bread
    • a serving of dairy is one cup of skim milk or yogurt or a 1.5 ounces of cheese
    • a serving size of meat, fish or poultry is about 3 ounces
    • a serving size of oil or salad dressing is 2 teaspoons
    • A serving size of alcohol depends on the drink that you choose. A serving of wine is 4 ounces, a serving of beer is 12 ounces and a serving of liquor is  1.5 ounces

    To find out how many servings of each food you should eat every day, you can use the USDA Supertracker.

    Serving size recommendations are based on your size, your gender and your activity level. You can visit their website to customize a plan for healthy eating or weight loss.


    Code of Federal Regulations-Food Labeling. U.S. Food and Drug Administration. Accessed: November 8,2015. http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=101.12

    Food Serving Sizes Getting a Reality Check. U.S. Food and Drug Administration. Accessed: November 8,2015. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm386203.htm

    Healthy Eating. Correct Portion Sizes: How to Keep Portion Distortion in Check. Dairy Council of California. Accessed: November 8, 2015. http://www.healthyeating.org/Healthy-Eating/Healthy-Living/Weight-Management/Article-Viewer/Article/348/correct-portion-sizes-how-to-keep-portion-distortion-in-check.aspx

    Medline Plus. Portion Size. U.S. National Library of Medicine. Accessed: November 8, 2015. https://www.nlm.nih.gov/medlineplus/ency/patientinstructions/000337.htm

    Portion Distortion. National Institutes of Health. Accessed: November 08, 2015. http://www.nhlbi.nih.gov/health/educational/wecan/eat-right/portion-distortion.htm

    Proposed Changes to the Nutrition Facts Label. U.S. Food and Drug Administration. Accessed: November 8,2015. http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm385663.htm

    Serving Size vs. Portion Size: Is There a Difference? Academy of Nutrition and Dietetics. Accessed: November 8, 2015. http://www.eatright.org/resource/food/nutrition/nutrition-facts-and-food-labels/serving-size-vs-portion-size-is-there-a-difference

    SuperTracker. My Plan. U.S. Department of Agriculture. Accessed: November 8, 2015. https://www.supertracker.usda.gov/myplan.aspx

    What is a Serving?. American Heart Association. Accessed: November 8,2015. http://www.heart.org/HEARTORG/Caregiver/Replenish/WhatisaServing/What-is-a-Serving_UCM_301838_Article.jsp#.Vj94ra6rTG5

    Continue Reading