Who Defines Serving Size? An Official Guide to Food Labeling

November 20, 2025 •

4 min read

According to the Food and Drug Administration (FDA), serving sizes are not dietary recommendations but are based on the amount of food and drink people typically consume. This clarification is crucial to understanding who defines serving size on the Nutrition Facts label and how that information should be interpreted by consumers for managing their food intake.

Quick Summary

Serving sizes are standardized by regulatory bodies like the FDA, based on consumption surveys, not on how much an individual should eat. The data, referred to as Reference Amounts Customarily Consumed (RACCs), ensures consistency across similar products for consumer comparison. Portions, however, are the amounts people choose to eat.

Key Points

FDA's Role: In the U.S., the FDA defines official serving sizes based on national consumption data, not as a dietary recommendation.
Consumption Data: Serving sizes are set using Reference Amounts Customarily Consumed (RACCs) derived from surveys like NHANES to reflect average intake.
Serving vs. Portion: A serving size is a standardized unit on the label, whereas a portion is the amount an individual chooses to eat.
Manufacturer's Responsibility: Manufacturers calculate the serving size based on regulatory standards and present it on the Nutrition Facts label.
Updated Labels: Recent FDA label updates have adjusted some serving sizes and introduced dual-column labels for packages with multiple servings.
Consumer Behavior: Misunderstanding the difference between serving and portion size can lead to unintended overconsumption and portion distortion.
Global Variations: Serving size regulations differ internationally, with some countries focusing on 100g/ml measures or dietary recommendations instead of typical consumption.

The Regulatory Bodies that Define Serving Size

Serving sizes are not arbitrary figures invented by food manufacturers. In the United States, the Food and Drug Administration (FDA) is the primary governmental body responsible for defining and regulating serving sizes on packaged food and beverage labels. Their definitions are not set as recommendations for a healthy diet, but rather as a standardized measure reflecting the quantity people typically consume in one sitting. This crucial distinction helps consumers compare the nutritional content of similar products more accurately.

How the FDA Determines Standardized Serving Sizes

The foundation of the FDA's serving size regulations are data-driven. The agency uses consumption data collected from national surveys, most notably the National Health and Nutrition Examination Surveys (NHANES), to determine the Reference Amounts Customarily Consumed (RACCs). These RACCs are the basis for setting the serving sizes that appear on the Nutrition Facts label. The FDA updates these amounts periodically to reflect changes in eating habits. For example, a 2016 update increased the reference amount for ice cream from half a cup to two-thirds of a cup to reflect more recent consumption patterns.

The Difference Between Serving Size and Portion Size

One of the most common sources of confusion for consumers is the interchangeable use of "serving size" and "portion size." While related, they are distinctly different terms with different meanings and applications.

Serving Size: This is the standardized, measured amount of food determined by regulatory bodies like the FDA, listed on the Nutrition Facts panel. All nutritional information (calories, fat, sodium) on the label corresponds to this specific amount.
Portion Size: This is the amount of food an individual chooses to eat at one time. A portion can be smaller, larger, or the same as the serving size listed on the label. Portion size is entirely within an individual's control, while serving size is a regulatory standard.

The Manufacturer's Role in Labeling

While the FDA provides the standardized Reference Amounts, the manufacturer is responsible for calculating and declaring the official serving size on their product's label. This calculation involves finding the number of whole units (e.g., biscuits, slices) that most closely approximates the RACC for that food category. The regulations ensure a practical and easy-to-understand household measure (like cups, ounces, or pieces) accompanies the metric weight in grams (g).

Global Variations in Serving Size Definitions

Serving size regulations are not uniform across the globe, as international bodies and national health agencies have their own methods. This variation affects how consumers interpret food labels and make comparisons.

A Comparison of Labeling Approaches


Feature	United States (FDA)	European Union (EU)	Australia & New Zealand	Mercosul Countries
Primary Basis for Regulation	Based on Reference Amounts Customarily Consumed (RACCs), reflecting actual consumption habits.	Based on Reference Intakes (RIs) and nutritional values per 100g/ml.	Based on average amounts customarily consumed, determined by manufacturers.	Based on recommendations for healthy consumption, alongside mandatory household measures.
Mandatory Information	Nutritional info per serving size, with dual-column labeling for larger packages.	Nutritional info per 100g/ml is mandatory, with info per serving being voluntary.	Nutritional info per 100g/ml and per serving is mandatory.	Nutritional info per serving and in household measures is mandatory.
Manufacturer Flexibility	Moderate; must adhere to established RACCs but has some flexibility in presentation.	High; manufacturer defines the serving size, which can lead to inconsistencies.	High; manufacturers determine the serving size but must justify it.	Varies by country, but regulations can have variation allowances.
Dual-Column Labeling	Required for packages between 200-300% of the RACC.	Not a standard requirement; presentation varies.	Not a standard requirement; presentation varies.	Not a standard requirement; presentation varies.

The Impact of Serving Size on Consumer Behavior

Research has shown that labeled serving sizes can have a significant impact on consumer perception and behavior. Consumers often misinterpret the serving size as a recommended portion, leading them to eat more or less than is appropriate for their individual needs. The growing availability of convenience foods with larger package sizes and multiple servings contributes to this issue, often leading to portion distortion. Educating the public about the difference between serving size and portion size is a key goal for public health initiatives.

Common Misconceptions

Misconception: "The serving size on the label is how much I should eat to be healthy." Reality: The label shows what's typical, not what's recommended for your specific dietary needs.
Misconception: "If the package says 'one serving,' that means the whole package is a single serving." Reality: The number of servings is listed on the label. Many packages contain multiple servings, even if they appear to be single-use.

The Importance of Labeling Clarity

Clear, standardized, and easily comprehensible food labels are vital for enabling consumers to make informed choices. The FDA's 2016 updates, which included changes to serving sizes, dual-column labeling, and mandatory 'added sugars' declarations, were aimed at improving this clarity. Initiatives that combine information presented per 100g/ml alongside serving size, as seen in some European models, can also enhance comparability between products.

Conclusion: Navigating the Complexities of Serving Size

In conclusion, the definition of serving size is a dynamic process shaped by regulatory agencies like the FDA and informed by population-wide consumption data. While the FDA determines the official serving size for labeling purposes, it is not a personalized recommendation. Consumers, therefore, must take an active role in understanding how to interpret this information. By distinguishing between the regulatory serving size and their personal portion size, consumers can make more informed dietary choices and navigate the complexities of food labeling effectively. Understanding who defines serving size is the first step toward reclaiming control over one's own nutrition.

Frequently Asked Questions

Yes, in the United States, the Food and Drug Administration (FDA) defines the official serving size for most packaged foods and beverages. These definitions are based on national food consumption surveys and not on dietary recommendations.

A serving size is a standardized, regulatory-defined amount found on the Nutrition Facts label, while a portion size is the amount of food an individual decides to eat. A portion can be larger or smaller than the official serving size.

The FDA determines serving sizes based on national food consumption surveys, which reveal how much of a particular food people typically eat or drink at one time. These standardized amounts are known as Reference Amounts Customarily Consumed (RACCs).

No, serving sizes are not dietary recommendations. They are standardized measurements intended to help consumers compare nutritional information between similar products. Individual dietary needs vary.

The FDA updated serving sizes in 2016 to better reflect current consumption habits, as eating patterns had changed since the original rules were established in 1993. The goal was to provide more realistic information.

A dual-column food label is required for certain packages that contain more than one, but less than three, servings. It shows nutrition information both on a 'per serving' basis and a 'per package' basis, making it easier for consumers who might eat the entire package at once.

The serving size is listed prominently at the top of the Nutrition Facts label on any packaged food product. It is often displayed in familiar household measures like cups, tablespoons, or pieces.

While manufacturers must adhere to the standardized Reference Amounts Customarily Consumed (RACCs) set by the FDA, they are responsible for calculating the serving size for their specific product based on these standards. International regulations can vary, with some giving manufacturers more leeway.