How is a "serving size" determined?

January 6, 2026 •

4 min read

According to the U.S. Food and Drug Administration (FDA), serving sizes are not dietary recommendations but are based on Reference Amounts Customarily Consumed (RACCs), which are established from national food consumption surveys. This regulatory guideline dictates the standardized amount of food you see on a Nutrition Facts label.

Quick Summary

Serving sizes are determined by the FDA using national food consumption data and standardized Reference Amounts Customarily Consumed (RACCs). They represent the amount typically eaten, not a recommended portion. This figure helps standardize nutrition labels for packaged foods.

Key Points

FDA Regulation: The FDA determines serving sizes based on national food consumption surveys, not on what people should eat.
RACC Definition: The key tool is the Reference Amount Customarily Consumed (RACC), a standardized reference amount for over 150 food categories.
Typical Consumption: Serving sizes reflect the amount of food or drink people typically consume in a single sitting.
Serving vs. Portion: A serving size is a regulated labeling standard, while a portion size is the amount an individual chooses to eat.
Labeling Units: Serving sizes are displayed on the label in common household measures (e.g., cups) and metric units (grams/mL).
Dual-Column Labels: The FDA mandates dual-column labels for packages that can be consumed in one sitting but contain more than one serving, to show both 'per serving' and 'per package' nutrition info.

The Core Principle: What People Actually Eat

Many people mistakenly believe that the serving size listed on a food label is a recommendation for how much they should eat. The reality is quite different. Federal regulations mandate that serving sizes be based on the amount of food or beverage that people typically consume in a single sitting. This principle is the cornerstone of serving size determination. This crucial distinction means that a serving size is a descriptive statistic of public eating habits, not a prescriptive health guideline. For example, a food company cannot arbitrarily decide that a single-serving bottle of soda is 8 ounces; if national survey data shows that people now typically drink 12 ounces in one sitting, the serving size must be updated to reflect that change. This shift, which occurred with the updated Nutrition Facts label, helps ensure consumers get more accurate information based on real-world eating patterns.

The Role of Reference Amounts Customarily Consumed (RACCs)

At the heart of the FDA's process are the Reference Amounts Customarily Consumed (RACCs). These are the specific, standardized reference amounts that the FDA has established for over 150 different food and beverage categories. Food manufacturers must use these RACCs to calculate the official serving size for their products. For instance, the RACC for yogurt is 6 ounces, while for ice cream it was updated from ½ cup to ⅔ cup to reflect changing consumer behavior.

How RACCs are used to determine serving size:

A manufacturer identifies the appropriate RACC for their product's category.
They then use a specific set of rules to convert the RACC into a common household measure, such as cups, tablespoons, or pieces.
For bulk products like cereal, the serving size is the household measure closest to the RACC. For discrete units like cookies, the serving size is the number of units that approximates the RACC.
The final serving size is listed on the Nutrition Facts label in both household units and metric units (grams or milliliters).

The Difference Between Serving Size and Portion Size

This is one of the most important concepts to grasp when reading a nutrition label. While a serving size is a standardized, regulated amount for labeling, a portion size is the amount of food or drink a person chooses to consume. This amount can be much larger or smaller than the official serving size. The growth of portion sizes, particularly in restaurant meals and packaged goods, has contributed to increased calorie consumption and is a major public health concern. Being mindful of this distinction is critical for managing calorie intake and making healthier choices.

The rise of dual-column labeling

To address the issue of oversized single-serving packages, the FDA introduced dual-column labels for certain products. This applies to products that contain between one and two times the standard serving amount but could reasonably be eaten in a single sitting, like a 20-ounce soda or a pint of ice cream. The label must show nutritional information both on a 'per serving' basis and a 'per package' basis, making it easier for consumers to understand the total calorie and nutrient intake if they consume the whole item at once.

Comparison: Serving Size vs. Portion Size


Feature	Serving Size	Portion Size
Determined by	U.S. Food and Drug Administration (FDA) regulations based on consumer data.	The individual consumer's choice at a given time.
Purpose	To standardize nutrition information on food labels for comparison.	To fulfill personal hunger or desire for food.
Measurement	Standardized household units (e.g., 1 cup, 3 cookies) and metric units (e.g., g, mL).	Can be any amount—the amount put on a plate, eaten out of a container, etc..
Guideline	A historical snapshot of typical consumption, not a health recommendation.	Influenced by personal factors like appetite, plate size, and social setting.
Variable?	Remains consistent for a specific product and food category across different brands.	Varies dramatically from person to person and from meal to meal.

Conclusion

Understanding how serving size is determined is key to deciphering food labels accurately and making informed dietary decisions. Serving size is not a prescriptive rule for eating but a reflection of typical consumption habits, standardized and regulated by the FDA based on national surveys like NHANES. By understanding the science and regulation behind serving sizes, consumers can better translate the numbers on the Nutrition Facts label into a clearer picture of their own portion control. It empowers individuals to take responsibility for the portions they choose to eat, rather than blindly following a number on a package, thereby aiding in the pursuit of a healthy and balanced diet.

Additional Resources

For more detailed information on serving sizes and food labeling, visit the official Food and Drug Administration website: Understanding the Nutrition Facts Label.

Frequently Asked Questions

The primary factor is the amount of food or beverage that is customarily consumed by the general population in one sitting, as determined by the FDA using national food consumption data.

No, serving sizes are not health recommendations. They are a standardized measurement used to compare the nutritional content of similar products based on typical eating habits.

RACCs (Reference Amounts Customarily Consumed) are standardized reference amounts established by the FDA for various food categories. Food manufacturers must use the appropriate RACC to calculate the serving size for their product.

Serving sizes changed because the FDA updated its national consumption data. For example, the serving size for ice cream increased from ½ cup to ⅔ cup because people now typically consume more in one sitting.

A serving size is the standard amount listed on a label for nutritional comparison, while a portion size is the amount of food an individual actually chooses to eat.

A dual-column label shows nutritional information for both a single serving and the entire package. It is required for products that could be eaten in one sitting but contain more than one serving, such as a large soda bottle.

Consumers should use the serving size to calculate the total calories and nutrients if they eat more than one serving. This helps them accurately manage their intake and understand their dietary choices.