How are serving sizes determined? A look at FDA regulations

November 1, 2025 •

4 min read

According to the U.S. Food and Drug Administration (FDA), a serving size is a standardized amount of food that reflects the amount people typically eat or drink, not the recommended amount. The seemingly simple numbers on a Nutrition Facts label are the result of extensive research and regulatory oversight, ensuring that the information accurately represents real-world consumption habits to help consumers make informed dietary choices.

Quick Summary

The FDA relies on national consumption surveys to establish Reference Amounts Customarily Consumed (RAACs), which form the basis for all official serving sizes on food labels. These standardized amounts, expressed in common household measures, have been periodically updated to reflect changes in American eating patterns. Understanding this process clarifies the difference between serving size and your actual food portion.

Key Points

RAACs are the Foundation: The FDA determines serving sizes based on Reference Amounts Customarily Consumed (RAACs), which are standardized amounts of food that reflect what people typically eat in one sitting.
Consumption Data Drives Change: Serving sizes are not static; the FDA periodically updates RAACs based on national consumption surveys to ensure they accurately reflect current eating habits.
Serving vs. Portion: A serving size is a regulated, standardized amount on a food label, whereas a portion size is the amount of food an individual chooses to eat.
Dual-Column Labels: Updated FDA regulations require dual-column labels for some packages to show nutrition information both per serving and per container, helping consumers understand the total intake if they eat the whole package.
Visuals Influence Behavior: Factors like packaging size and imagery can act as implicit consumption cues, influencing the portion size a person serves themselves and potentially leading to overconsumption.
Don't Confuse with Recommendations: The official serving size on a food label is a reporting benchmark, not a dietary recommendation for how much you should eat.

The Core Concept: Reference Amounts Customarily Consumed (RAACs)

At the heart of how are serving sizes determined is a concept known as the Reference Amount Customarily Consumed (RACC). The RACC is a standardized, science-based value set by the FDA that represents the amount of food the average person typically consumes in a single eating occasion.

To establish these reference amounts, the FDA analyzes data from national food consumption surveys, such as the National Health and Nutrition Examination Survey (NHANES). The RACC is not a dietary recommendation but a regulatory benchmark, ensuring that nutrition information is consistent and comparable across similar products.

How RAACs Lead to a Serving Size

To translate a RACC into a serving size, manufacturers follow a specific procedure:

Categorization: First, they identify the appropriate product category from the FDA's extensive RACC tables. This step ensures that similar foods, like all brands of ice cream or chips, use the same reference amount.
Household Measurement: The RACC, typically listed in grams (g) or milliliters (mL), is then converted into a more familiar "household measure," such as a cup, tablespoon, or number of pieces.
Calculation and Rounding: The manufacturer calculates the amount that most closely approximates the RACC. For example, if the RACC for chips is 28g (1 ounce), and a single chip weighs 2g, the serving size on the label might be listed as "about 14 chips (28g)". Rounding rules are applied to ensure the household measure is practical for consumers.

Updated Regulations and Dual-Column Labels

In 2016, the FDA mandated significant updates to the Nutrition Facts label, primarily to reflect more current consumption data.

Reflecting Reality: The updated regulations saw some serving sizes increase and others decrease to better match what people actually eat. For instance, the RACC for ice cream was changed from ½ cup to ⅔ cup to reflect actual consumption, while the RACC for yogurt decreased from 8 ounces to 6 ounces.
Single-Serving Packages: The new rules require that items typically eaten in one sitting, even if they contain more than one RACC, be labeled as a single serving. A 20-ounce bottle of soda, for example, is now listed as one serving.
Dual-Column Labels: For packages containing between two and three servings, dual-column labels are now required. These labels provide nutrition information per serving and per container, making it easier for consumers to understand the total calorie and nutrient intake if they eat the entire package.

Serving Size vs. Portion Size: The Key Distinction

This is one of the most common points of confusion for consumers. A serving size and a portion size are not the same thing, though the terms are often used interchangeably.

Comparison of Serving and Portion


Aspect	Serving Size	Portion Size
Definition	A standardized, regulated amount of food or drink.	The amount of food you choose to eat at one time.
Determined by	The FDA, based on national consumption data (RAACs).	The individual consumer, influenced by hunger, plate size, and social cues.
Purpose	To provide a consistent, comparable basis for nutritional information.	To satisfy one's appetite and personal preference at a given moment.
Measurement	Standardized units like cups, ounces, grams, or pieces.	Highly variable and not standardized. Can be more or less than a serving size.

Factors Beyond RAACs Affecting Serving Size Perception

While regulatory bodies set the official serving size, consumer perception and behavior are influenced by many other factors.

Visual Cues: Studies have shown that package size and the images of food on packaging can act as implicit consumption norms, influencing how much a person serves themselves. Larger packaging can inadvertently lead to consuming a larger portion.
Product Marketing: Companies may sometimes exploit serving sizes to make a product seem healthier. For instance, listing a smaller, less realistic serving size can reduce the apparent calorie or sugar content per serving, though labeling laws are now stricter on this.
Social and Emotional Factors: Our eating habits are not purely based on biological hunger. Psychological research indicates that factors like gender, age, and emotional state can significantly impact the size of the portion we select for ourselves.

Using Serving Size Information Effectively

For health-conscious consumers, understanding how to use the information on the Nutrition Facts label correctly is crucial. It requires going beyond simply reading the serving size and looking deeper into the data provided.

Calculate Based on Your Portion: If you eat a larger portion than the listed serving size, remember to scale the nutritional values accordingly. For a product with two servings per container, eating the whole package means doubling the calories, fats, and sugars.
Compare Products: Use the standardized serving sizes to compare the nutritional profiles of similar products accurately. This is the primary benefit of the RACC system. For example, compare the amount of sodium or fiber per serving between two different brands of soup.
Visualize the Measurement: Many health guides recommend using common objects or your own hand as a visual guide for estimating portions. For example, a deck of cards is a good approximation for a 3-ounce serving of meat.

Conclusion

Understanding how serving sizes are determined reveals that they are not arbitrary recommendations but carefully standardized measurements based on real consumer habits. These regulatory values, or RAACs, provide a transparent and consistent way to compare the nutrition content of different foods. While a serving size offers a regulated reference point, the amount you actually eat—your portion—is influenced by many personal and environmental factors. By learning to differentiate between these two concepts and properly interpreting the information on food labels, consumers can make more informed and mindful choices about their dietary intake.

Frequently Asked Questions

In the United States, the Food and Drug Administration (FDA) determines the official serving sizes for packaged foods. They base these amounts on national surveys that measure how much people typically consume.

A serving size is a standardized, regulated amount on a food label used for nutrition reporting. A portion size is the amount of food an individual chooses to eat, which can be more or less than the labeled serving.

RAAC stands for Reference Amount Customarily Consumed. These are the standardized, science-based values established by the FDA that serve as the foundation for determining serving sizes on food and beverage labels.

In 2016, the FDA updated its regulations to reflect more current eating habits. This led to changes like increasing the serving size for ice cream (from ½ cup to ⅔ cup) and decreasing it for yogurt (from 8 ounces to 6 ounces).

A dual-column label appears on certain packages that might be consumed in a single sitting. It lists the nutrition information for both a single serving and for the entire package, making it easier to track your total intake.

No, the serving size on a label is not a recommendation. It is a reference amount to provide standardized nutritional information, not dietary advice. Your personal portion may vary based on your dietary needs.

While some companies may have historically used smaller, unrealistic serving sizes to make their products appear healthier, the FDA's updated regulations are designed to prevent this. Rules now require serving sizes to more accurately reflect typical consumption.