In this guide to serving size vs. portion size, we’ll clear up the confusion by clarifying what each term means.

Many people use the terms serving size and portion size interchangeably, even though they don’t mean the same thing.^[1] You don’t want to confuse the two because it has the potential to cause diet-tracking mistakes, misinformed eating habits, and weight management issues.

Let’s discuss the differences, examples, and practical tips for using portion and serving sizes to your advantage. 

What are serving sizes?

A serving size is a standardized measurement of food or drink. It is designed to reflect how much of that particular food people typically eat and isn’t meant to be a recommendation for how much to consume. For example, a 3-ounce bag of chips may consist of 3, 1-ounce servings, but you can eat the whole bag at once.^[2]

The Food and Drug Administration (FDA) requires that serving sizes be listed on all packaged foods and drinks. You can typically find it on Nutrition Facts labels.^[3]  

Besides the serving size, a Nutrition Facts label must accurately display the calories and available nutrients per serving. This vital dietary information simplifies comparing foods, making informed eating decisions, and tracking nutrient intake.

Here are examples of typical serving sizes for different foods (but note that serving sizes will vary depending on the specific type of food listed and how it’s prepared):^[4]

• 1 cup of cereal
• 1 slice of bread
• 1 cup of cooked rice or pasta
• 2 cups of lettuce
• 3 ounces of meat, poultry, or fish
• 1 ounce of nuts or seeds  
• 1 cup of milk
• 1½ ounces of cheese (could vary by cheese type)
• 2/3 cup of ice cream

What are portion sizes?

Portion size is the quantity of food you eat in a sitting. Unlike serving sizes, which are more standardized across food products, portion sizes typically vary more between individuals. For instance, you might eat a single slice of pizza while your friend eats several. 

Various factors can influence your portion size, including personal preference, hunger, available food, budget, health, and so on.^[5] These factors can also cause fluctuations in portion sizes between meals. For example, say you had 2 burgers for lunch but 1 for dinner because you were less hungry.

While it’s not compulsory, you can portion meals according to the serving size listed on a food label. Alternatively, use the provided serving size and nutrient information to calculate calories and nutrients for your preferred portion size. 

In the end, what truly matters is that you eat an amount that meets your dietary needs and health goals. 

Say you’re trying to build muscle, for example. Instead of 3 ounces of chicken (an example of what might equal 1 serving), you might make your portion 6 ounces to increase your daily protein intake for muscle growth. 

Serving size vs. portion size: Key differences

To help clear the confusion between portion and serving size, here’s a breakdown of their differences: 

• Standardization: Comparing portion vs. serving size, the primary difference is that serving size is a standardized measurement of food listed on Nutrition Facts labels. Portion sizes, on the other hand, aren’t listed on labels and vary between individuals.^[6]
• Purpose: Serving size provides nutritional information for a specific quantity of food, while portion size reflects a person’s actual food consumption.
• Source: Another crucial serving size vs. portion size difference is the FDA sets serving sizes.^[7] In contrast, you decide your portion sizes based on hunger, preferences, resources, or habits.
• Consistency: Serving sizes are consistent across labels for specific products, while portion sizes will fluctuate between individuals and even meals. 

An example that demonstrates the difference between portion size vs. serving size is serving yourself a large plate of pasta. This isn’t 1 serving, but 1 portion. On the other hand, a serving of pasta might be closer to 1 cup, which might not be filling enough if you’re particularly hungry.

Challenges with serving sizes and portions

The rewards for using serving and portion sizes to eat healthy are numerous. For instance, the nutrition and calorie information displayed with serving sizes on food labels can help you portion meals to avoid overeating.

However, applying portion and serving sizes can come with some challenges, such as:

• Serving size vs. portion size confusion: A 2022 study revealed that 48% of Americans confuse portion and serving size.^[8] This leads to misconceptions like serving size equals what you should eat.^[9] In reality, serving size is not a recommendation but a standardized representation of how much a person typically eats.^[10]
• Serving size adjustments: The FDA has changed serving sizes for multiple foods over the years.^[11] These changes may confuse consumers, leading to misinformed dietary decisions.
• Portion distortion: Like serving sizes, portion sizes have gotten bigger over the years.^[12] This increase in portions served in homes and restaurants has contributed to overeating and weight gain.^[13]
• Misleading marketing and packaging: Some restaurants and packaged foods offer larger portions than nutritional guidelines recommend.^[14] This can cause consumers to eat more than they perhaps should.

How to measure and control portion sizes

You’ve read our serving size vs. portion size comparison and now understand their difference. But if 1 serving isn’t equal to 1 portion, how do you measure portions? Here are useful tips for measuring and controlling your portion sizes:

• Use measuring cups: With measuring cups, you can portion foods like cereal, rice, and pasta to prevent overeating. 
• Alternatively, use food scales: An alternative to measuring cups is kitchen scales. With a scale, you can accurately portion proteins, vegetables, and other foods by weight. 
• Compare portions to everyday objects: A 3-ounce steak is about the size of a deck of cards or the palm of your hand. A cupped hand of grains is about half a cup, and 1 ounce of cheese is comparable to a one-inch square or a pair of dice. You can use this technique to estimate the quantity of various foods.
• Incorporate mindful eating techniques: Effective mindful eating techniques include eating slowly and only when hungry. By eating slowly without distractions, you’re less likely to eat more than you intended. You can also notice when you’re comfortably full and stop eating to prevent overeating.

Tools to help you understand serving and portion sizes

Making the most of serving and portion sizes is easier with the right tools. Here are some user-friendly tools you can try:

1. MyPlate Guide: USDA’s MyPlate food groups guide teaches how to balance meals to include the 5 essential foods (dairy, fruits, vegetables, grains, and protein) and offers daily recommended amounts for each food group. This ensures a balanced and nutritious diet.
2. Portion control plates: These have compartments for different foods. Each compartment’s limited size helps keep portions in check.
3. Food scales and measuring cups: With these tools, you can accurately measure and compare serving sizes vs. portion sizes. You can then portion meals into quantities that meet your needs.

Finding balance in serving and portion sizes

Serving size indicates how much of a particular food the average person eats in a sitting. In contrast, portion size is the actual food quantity you eat in a sitting. But don’t forget that serving size isn’t necessarily a recommendation for how much you should eat. 

Knowing the difference between serving size vs. portion size is key to managing your food intake and making better eating decisions. With tools like USDA’s MyPlate, understanding serving sizes and portioning meals becomes simpler. 

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Serving vs. Portion Sizes FAQs 

How can I determine the correct serving size for foods?

The standardized serving size for every packaged food is visible on its Nutrition Facts label. For unpackaged foods, USDA’s MyPlate is a reliable resource that lists the recommended daily intake for various foods.^[15]

What impact do portion sizes have on nutrition?

Portion sizes affect how much you eat in a sitting. A too-small portion may lead to lingering hunger and inadequate nutrition, while a too-large portion can cause overeating and weight gain

Sources

[1] Food Insight. Consumer Survey: Understanding Portion and Serving Sizes. Last reviewed January 26, 2022. https://foodinsight.org/consumer-survey-understanding-portion-and-serving-sizes/

[2] National Heart, Lung, and Blood Institute. Serving Sizes and Portions. Last reviewed September 30, 2013. https://www.nhlbi.nih.gov/health/educational/wecan/eat-right/distortion.htm

[3] U.S. Food and Drug Administration (FDA). What’s on the Nutrition Facts Label? Last reviewed March 5, 2024. https://www.fda.gov/food/nutrition-facts-label/whats-nutrition-facts-label

[4] U.S. Food and Drug Administration (FDA). Reference Amounts Customarily Consumed: List of Products for Each Product Category: Guidance for Industry. Last reviewed January 8, 2025. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101

[5] National Library of Medicine. Gender, Age, Hunger, and Body Mass Index as Factors Influencing Portion Size Estimation and Ideal Portion Sizes. Last reviewed May 11, 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9130823/

[6] U.S. Food and Drug Administration (FDA). Serving Size on the Nutrition Facts Label. Last reviewed March 5, 2024. https://www.fda.gov/food/nutrition-facts-label/serving-size-nutrition-facts-label

[7] U.S. Food and Drug Administration (FDA). Serving Size on the Nutrition Facts Label. Last reviewed March 5, 2024. https://www.fda.gov/food/nutrition-facts-label/serving-size-nutrition-facts-label

[8] International Food Information Council. IFIC Study Serves Up Reality Check on Serving, Portion Sizes. Last reviewed January 26, 2022. https://ific.org/media-information/press-releases/ific-study-serves-up-reality-check-on-serving-portion-sizes/

[9] International Food Information Council. IFIC Study Serves Up Reality Check on Serving, Portion Sizes. Last reviewed January 26, 2022. https://ific.org/media-information/press-releases/ific-study-serves-up-reality-check-on-serving-portion-sizes/

[10] Integris Health. What is the Difference Between Serving Size and Portion Size? Last reviewed May 8, 2023. https://integrishealth.org/resources/on-your-health/2023/may/serving-size-and-portion-size

[11] U.S. Food and Drug Administration (FDA). Food Serving Sizes Have a Reality Check. Last reviewed March 30, 2022. https://www.fda.gov/consumers/consumer-updates/food-serving-sizes-have-reality-check

[12] UF/IFAS, University of Florida. Portion Control Matters. Portion Size Matters. Last reviewed January 13, 2023. https://blogs.ifas.ufl.edu/browardco/2023/01/13/portion-control-matters-portion-size-matters/

[13] National Library of Medicine. Yes, Food Portion Sizes and People Have Become Bigger and Bigger. What Is to Be Done? Last reviewed December 11, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8667827/

[14] Center for Science in the Public Interest. Restaurant Portions Are Out of Control. We Measured 11 Supersized Ones. Last reviewed January 26, 2023. https://www.cspinet.org/article/restaurant-portions-are-out-control-we-measured-11-supersized-ones

[15] U.S. Department of Agriculture (USDA) MyPlate. What is MyPlate? https://www.myplate.gov/eat-healthy/what-is-myplate

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