How Do They Decide What a Serving Size Is? A Deep Dive Into Nutrition Labels

December 15, 2025 •

3 min read

In 2016, the FDA famously updated the serving size for ice cream from a half-cup to two-thirds of a cup, a change reflecting modern consumption habits. This shift begs the question: How do they decide what a serving size is, and why does it matter for what we eat?

Quick Summary

Serving sizes on packaged foods are standardized by regulatory bodies like the FDA, based on data reflecting amounts people typically consume, not a recommendation for a healthy diet. This is different from a portion, which is the amount you choose to eat.

Key Points

Based on Consumption, Not Recommendations: Serving sizes are determined by surveys of how much people actually consume, not by dietary guidelines.
FDA's Role: In the U.S., the Food and Drug Administration (FDA) is responsible for setting and updating these standardized serving sizes using data from national surveys.
Reference Amounts Customarily Consumed (RACC): The FDA uses specific Reference Amounts Customarily Consumed (RACCs) for each food category to ensure consistency in serving size declarations.
Serving vs. Portion: A serving size is a reference amount on a label, while a portion is the amount of food you choose to eat. Your portion may be larger or smaller than the serving size.
Label Updates: The FDA updated the Nutrition Facts label to use larger fonts for calorie and serving information and added dual-column labels for certain products to show nutrition for both a single serving and the whole package.
Comparative Tool: Standardization through RACCs allows for fair, side-by-side comparisons of the nutritional content of similar food products.

The Core Concept: Reference Amounts Customarily Consumed (RACC)

Serving sizes on food labels in the U.S. are primarily determined by the Food and Drug Administration (FDA) through a concept called "Reference Amounts Customarily Consumed" (RACC). RACCs are not based on dietary guidelines but on national surveys like the National Health and Nutrition Examination Survey (NHANES), which collect data on actual food and drink consumption. This approach ensures that serving sizes are realistic and relatable to how people typically consume products. The aim is to standardize serving sizes within product categories to allow consumers to compare the nutritional content of similar items effectively.

The Crucial Distinction: Serving Size vs. Portion Size

It's important to understand the difference between serving size and portion size, as they are not the same thing.

Serving Size

Standardized: Set by regulatory bodies based on consumption data.
Purpose: To provide a consistent reference point for comparing the nutritional value of different foods.

Portion Size

Individual: The amount an individual chooses to eat at one time.
Variable: Can be more or less than the serving size and may contain multiple servings.

Updates to Nutrition Facts Labels and Their Implications

The FDA updated the Nutrition Facts label to better reflect current eating habits. These updates included revising RACCs, which led to changes in reported serving sizes for many foods and beverages. For certain packages that contain between 200% and 300% of the RACC, the new labels feature a dual-column format displaying nutritional information per serving and per package. Containers with less than 200% of the RACC are typically labeled as a single serving.

Converting RACCs to Household Measures

After determining the RACC in grams or milliliters, manufacturers translate this into a common household measure (like cups or pieces) to make the label easier for consumers to understand. This conversion requires adherence to FDA guidelines to maintain consistency.

The Role of Serving Size in Dietary Awareness

Understanding how serving sizes are determined can help consumers make more informed decisions. It clarifies that the serving size is a tool for understanding nutritional content and comparing products, not a dietary recommendation. By using the serving size as a reference, individuals can better manage their portion sizes within their overall diet. The FDA provides resources on how to effectively use the Nutrition Facts label for dietary awareness, such as their guide titled "How to Understand and Use the Nutrition Facts Label." [Link: https://www.fda.gov/food/nutrition-facts-label/how-understand-and-use-nutrition-facts-label]


Feature	Serving Size	Portion Size
Determined by	Regulatory agencies (e.g., FDA)	Individual choice
Based on	Average amount people consume	Hunger, mood, preference
Primary Purpose	Standardized nutritional comparison	How much food you actually eat
Where to Find	On the Nutrition Facts label	Determined by the individual
Example	1/2 cup of rice	1 full cup of rice eaten for dinner

Conclusion

Serving sizes on food labels are established by regulatory bodies based on how much people typically eat, serving as a standardized reference for nutritional comparison. They are distinct from portion sizes, which are the amounts individuals choose to consume. Recent updates to labels aim to provide clearer information, including dual-column labels for some products, empowering consumers to make better-informed food choices.

Frequently Asked Questions

In the United States, the Food and Drug Administration (FDA) is responsible for setting the official serving sizes. These are based on extensive food consumption surveys rather than dietary recommendations.

A serving size is a standardized, measured amount of food listed on the Nutrition Facts label, used for nutritional comparison. A portion size is the amount of food an individual chooses to eat at one time, which can vary from person to person.

A RACC is the official term used by the FDA to describe the amount of food the average person is expected to eat in one sitting. It's the basis for calculating the serving size on a food label.

The FDA updated serving sizes in 2016 to reflect more current consumption patterns, as eating habits had changed significantly since the previous rules were established in 1993. This included adjusting quantities for items like ice cream and soda.

A dual-column label is a format required for certain food packages (between 200-300% of the RACC) that shows nutritional information for both a single serving and the entire container. This helps consumers easily see the total impact of eating the whole package at once.

No, the serving size is not a recommendation for how much you should eat. It is a standardized reference point to help you interpret the nutrition information on the label.

Once the RACC is established in metric units (grams or milliliters), the FDA provides guidelines for converting it into a common household measure (e.g., cups, tablespoons, or pieces) that is most appropriate for the food.

You can use the serving size as a tool for portion control by comparing the nutrients in a single serving to your total daily diet. By understanding that a large package may contain multiple servings, you can make more informed decisions about how much to consume.