How many calories are in 80 g of white onion? A nutritional analysis

November 27, 2025 •

4 min read

Did you know that an 80-gram serving of raw white onion contains approximately 32 calories, making it an incredibly low-calorie and flavorful addition to any meal? This specific portion size offers a fantastic way to boost taste and nutritional value without significantly impacting your daily caloric intake.

Quick Summary

An 80-gram portion of raw white onion provides approximately 32 calories, along with fiber, vitamins, and beneficial plant compounds. This low-fat, low-sodium vegetable is an excellent way to add significant flavor and nutrients to your diet without adding excess calories.

Key Points

Calorie Count: An 80g serving of raw white onion contains approximately 32 calories.
Low Fat and Sodium: White onions are naturally very low in fat and sodium, making them heart-healthy.
Rich in Antioxidants: Contains powerful antioxidants like quercetin, which helps fight inflammation.
Good for Digestion: Provides prebiotic fiber that promotes a healthy gut microbiome.
Preparation Affects Calories: Sautéing or frying with oil will increase the calorie count significantly, while raw or roasted preparation keeps it low.
Nutrient-Dense: Supplies vitamins C and B6, plus minerals like potassium and manganese.

Understanding the Calorie Count in White Onions

An 80-gram portion of raw white onion, which is roughly equivalent to a small to medium-sized onion or half a cup of chopped onion, contains about 32-35 calories. This low energy density is one of the many reasons onions are a cornerstone of healthy cuisine. The majority of these calories come from carbohydrates, while the vegetable contains negligible amounts of fat and a small amount of protein. Knowing the precise calorie and nutrient content of everyday ingredients like white onions empowers you to make informed dietary choices and effectively manage your caloric goals.

The Full Nutritional Profile of 80g of Raw White Onion

Beyond just the calorie count, 80g of raw white onion offers a spectrum of valuable nutrients:

Carbohydrates: Approximately 7 grams, primarily from natural sugars and fiber.
Dietary Fiber: About 1 gram, which aids in digestion and promotes gut health.
Protein: Around 1 gram.
Fat: A minimal 0.1 gram, making it nearly fat-free.
Water: The vast majority of the onion's weight is water, about 89%.

Additionally, this portion provides an array of essential vitamins and minerals:

Vitamin C: An antioxidant that supports immune function.
Vitamin B6: Important for metabolism and red blood cell production.
Folate (B9): A crucial nutrient, especially for cell growth.
Potassium: Helps regulate fluid balance and blood pressure.
Manganese: An essential trace mineral involved in many bodily functions.

Comparison: Raw vs. Cooked White Onion

How you prepare your white onion can significantly affect the final calorie count of your dish, mainly due to added fats. While the onion itself remains low-calorie, sautéing or frying in oil will increase the total energy content. The table below illustrates the caloric difference based on cooking method.


Ingredient (80g)	Preparation	Calories (Approx.)	Notes
Raw White Onion	Raw, chopped	32 kcal	No added fats or oils.
Sautéed White Onion	Sautéed in 1 tsp olive oil	72 kcal	Adds about 40 kcal from the oil.
Caramelized White Onion	Slowly cooked in butter/oil	80+ kcal	Calorie count varies by fat and sugar content.
Raw Red Onion	Raw, chopped	26-30 kcal	Similar to white, slightly less sweet.

The Health Benefits of White Onions

White onions offer numerous health benefits that extend far beyond their low-calorie profile. They are packed with antioxidants and organosulfur compounds, which have been studied for their potential protective effects.

Antioxidant Powerhouse: Onions are a rich source of flavonoids, particularly quercetin, a powerful antioxidant that helps fight inflammation and cellular damage.
Supports Heart Health: The organosulfur compounds and quercetin in onions may contribute to lower cholesterol and blood pressure, reducing the risk of heart disease.
Promotes Digestive Health: The prebiotic fiber, specifically fructans, found in onions feeds beneficial gut bacteria. This can lead to a healthier gut microbiome and improved digestion.
Potential Cancer-Fighting Properties: Some studies suggest that the compounds in allium vegetables like onions may inhibit tumor growth, though more research is needed.
Helps Control Blood Sugar: Compounds in raw onions have shown potential to help manage blood sugar levels, particularly in those with type 2 diabetes.

Maximizing the Flavor and Health of Your Onions

For those looking to get the most nutritional bang for their buck, there are several ways to incorporate white onions into your diet effectively:

Eat Them Raw: Slicing raw white onion for salads, sandwiches, and tacos is an excellent way to get maximum nutritional benefit, especially from its sulfur compounds.
Use as a Base: Dicing onions for soups, stews, and sauces adds a deep, savory flavor without needing extra fat. Start your cooking by sweating the onions over low heat until translucent.
Roast or Grill: Cooking onions in the oven or on the grill with a minimal amount of oil brings out their natural sweetness, creating a delicious side dish or topping.
Pickle Them: Pickled onions are a tangy, delicious condiment that maintains many of the raw onion's benefits while offering a different flavor profile. The pickling process doesn't add significant calories unless sugar is introduced.
Blend into Dips: Pureeing raw or lightly cooked white onions into dips and spreads, like hummus or guacamole, is a great way to add flavor and nutrients. For more ideas on how to incorporate healthy vegetables, check out this resource.

Conclusion

In summary, 80 grams of raw white onion is a low-calorie, nutrient-dense ingredient that can significantly enhance the flavor and health benefits of your meals. With only about 32 calories per serving, it's rich in vitamins, minerals, and potent antioxidants like quercetin, which support heart and digestive health. While the calorie count can increase depending on how it's prepared, the onion itself remains a powerhouse of nutrition. Whether you enjoy it raw, cooked, or as a flavoring base, white onion is a versatile and healthy choice for any diet.

Frequently Asked Questions

The calorie count for 80 g of cooked white onion depends on the cooking method. If boiled or roasted without added fat, the calorie count remains similar (32-35 kcal). However, sautéing in oil can add 40 calories or more, significantly increasing the total count.

Raw white onion retains more of its heat-sensitive nutrients, such as Vitamin C and certain sulfur compounds, which can be diminished by cooking. However, cooked onions can also have health benefits, and both are excellent for a healthy diet.

Yes, red, yellow, and white onions have very similar calorie counts per gram, with some minor variations based on sweetness and water content. The main nutritional difference lies in the types and quantities of specific antioxidants, with red onions often having more anthocyanins.

White onions are a good source of Vitamin C, Vitamin B6, Folate, and essential minerals like potassium and manganese. They are also high in prebiotic fiber and powerful antioxidants.

Yes, white onions can support weight loss due to their low calorie and fat content, high water and fiber content, and ability to add significant flavor to meals. Using onions to flavor dishes can reduce the need for higher-calorie ingredients.

Adding raw or lightly cooked white onion will not significantly increase the calorie count of a dish due to its low energy density. The primary calorie increase comes from fats and oils used during the cooking process, not the onion itself.

Caramelizing white onions involves cooking them slowly, which breaks down sugars and reduces the water content. This intensifies sweetness and flavor. While some nutrients may be lost to heat, the main calorie increase comes from the butter or oil used during the process.