How many calories are in 100 gm of oats? Your Complete Nutrition Guide

December 12, 2025 •

4 min read

Approximately 379 to 389 calories are in 100 gm of raw, uncooked oats, a figure that drastically changes when the oats are cooked with water. This difference, primarily due to water absorption, is a crucial factor for anyone tracking their nutritional intake.

Quick Summary

This article breaks down the caloric content of 100g of raw versus cooked oats, details how preparation methods and added ingredients affect total calories, and compares different oat types to aid in dietary planning.

Key Points

Calorie Difference: Raw, dry oats contain approximately 379-389 calories per 100g, while cooked oats contain significantly fewer (~58 calories) per 100g due to water absorption.
Cooking Method Matters: Cooking oats in water does not add calories; it simply increases volume. The original calorie count of the dry oats portion remains constant.
Type of Oat: The fundamental calorie and nutrient profiles of steel-cut, rolled, and instant oats are similar when measured dry. The main differences are in texture, cooking time, and glycemic index.
Toppings Add Calories: The total caloric value of your oatmeal heavily depends on added ingredients like milk, sugar, nuts, and dried fruits, so choose wisely for weight management.
Rich in Health Benefits: Oats are a great source of fiber (especially beta-glucan), protein, and antioxidants, which support heart health, regulate blood sugar, and increase satiety.

Understanding the Calorie Count in 100g of Oats

When assessing how many calories are in 100 gm of oats, the key distinction lies in whether they are measured raw or cooked. The process of cooking oats, typically in water, adds no calories but significantly increases their volume due to water absorption. This means 100g of cooked oatmeal has far fewer calories than 100g of dry, uncooked oats.

Raw (Dry) Oats

For a standard reference serving of raw, dry oats, the caloric content is quite high because you are measuring a much denser product. According to various nutritional databases, 100g of uncooked rolled oats contains around 379 to 389 calories. This portion is a nutrient-dense source of carbohydrates, fiber, protein, and essential minerals.

Here is a typical nutritional breakdown per 100g of dry oats, based on aggregated data:

Calories: 379 kcal
Total Carbohydrates: ~68g
Dietary Fiber: ~10g
Protein: ~13g
Total Fat: ~6.5g

Cooked Oats

The perception of calories in oats changes dramatically once water is added. The calories per gram decrease because the water adds mass without adding energy. For example, 100g of cooked oatmeal (prepared with water) typically contains only around 58 calories. This happens because the initial 100g of dry oats absorbs approximately 300g of water during cooking, transforming into a much larger, lower-density portion. If you were to take a 100g serving of the finished porridge, it would contain only about 25g of the original oats, and the rest would be calorie-free water.

Different Oat Types: Calorie Breakdown

The type of oat—whether rolled, steel-cut, or instant—does not significantly alter the base caloric and nutritional values when measured in a dry, pre-cooked state. The differences lie in their processing, texture, cooking time, and glycemic index (GI), which affects how quickly your body converts the carbs into blood sugar. For weight management, focusing on portion size and toppings is more important than the oat variety.

Steel-Cut Oats: Minimally processed and coarser, they have a lower GI, leading to a slower release of energy and sustained fullness. Nutritionally, 100g dry is very similar to rolled oats.
Rolled Oats: Steamed and rolled into flakes, they cook faster than steel-cut oats but still maintain a relatively low GI. They are an excellent, versatile option.
Instant Oats: Finely rolled and pre-cooked, they have the shortest cooking time but the highest GI among the three. Some flavored instant oats also contain added sugars, significantly increasing the calorie count per serving.

Managing Total Calories with Add-ins

While the base calories in 100g of oats are predictable, the total calorie count of your breakfast can vary wildly depending on what you mix in. Choosing your toppings wisely is crucial for maintaining a healthy diet or controlling weight.

Low-Calorie Add-in Ideas

Berries: Fresh or frozen strawberries, blueberries, and raspberries add flavor, nutrients, and fiber with minimal calories.
Cinnamon and Spices: Spices like cinnamon, nutmeg, or a dash of vanilla extract add flavor without any calories.
Unsweetened Almond Milk: Choosing unsweetened plant-based milk instead of whole milk can save a significant number of calories.
A Pinch of Stevia: For a touch of sweetness without the added sugar, use a calorie-free sweetener.

Higher-Calorie Add-ins to Use in Moderation

Honey or Maple Syrup: While natural, these are still concentrated sources of sugar and calories.
Nuts and Nut Butter: Almonds, walnuts, and peanut butter are high in healthy fats and calories. Use in controlled portions.
Dried Fruit: Raisins, cranberries, and dates are calorie-dense due to their concentrated sugar content.

Oats vs. Other Grains: A Nutritional Comparison

To put oats' nutritional profile into perspective, here is a comparison of 100g (cooked) servings of common whole grains. The uncooked calorie density is much higher for all grains, but comparing the cooked servings provides a more practical dietary reference.


Nutrient (per 100g cooked)	Oats	Quinoa	Brown Rice
Calories	~68 kcal	~120 kcal	~111 kcal
Protein	~2.5g	~4.1g	~2.6g
Fiber	~1.7g	~2.8g	~1.8g

Note: Calorie and nutrient counts can vary slightly based on the cooking method and exact grain variety.

Health Benefits Beyond Calories

Oats offer numerous health advantages that extend far beyond their calorie content. The primary reason for their health reputation is the rich content of beta-glucan, a soluble fiber.

Heart Health: Beta-glucan has been proven to help lower total and LDL (bad) cholesterol, reducing the risk of cardiovascular disease.
Blood Sugar Control: The soluble fiber in oats slows digestion and glucose absorption, which helps stabilize blood sugar levels, especially beneficial for individuals with type 2 diabetes.
Promotes Satiety: Because beta-glucan increases the viscosity of food in the stomach, it delays stomach emptying and keeps you feeling full longer. This can help with weight management by reducing overall calorie intake.
Digestive Health: Both soluble and insoluble fiber aid in healthy digestion, helping prevent constipation and promoting a balanced gut microbiome.

Conclusion: Making Informed Choices

In summary, the number of calories in 100 gm of oats is approximately 379 kcal for raw oats and around 58 kcal for cooked oats prepared with water. The key takeaway is to always be aware of the state in which you are measuring your portion—dry or hydrated. While oats are a nutritional powerhouse packed with protein, fiber, and important minerals, the total caloric impact of your meal depends heavily on how you prepare them and what ingredients you add. By opting for minimally processed oats (steel-cut or rolled) and being mindful of high-calorie toppings, you can enjoy this versatile and healthy grain as part of a balanced diet. For further reading, consult the National Institutes of Health.

Low-Calorie, Nutritious Toppings

Fresh berries
Cinnamon and nutmeg
Unsweetened almond milk
Chia or flax seeds
A sprinkle of cocoa powder

High-Calorie Toppings (Use Sparingly)

Honey or maple syrup
Nuts and nut butter
Dried fruit
Brown sugar
Chocolate chips

Frequently Asked Questions

A 100g serving of oats cooked in water contains approximately 58 calories. The reason for the much lower calorie count compared to raw oats is the water absorbed during cooking, which adds mass without adding calories.

No, cooking oats in water does not change their caloric content. The energy density decreases because the mass increases with the addition of calorie-free water. The total calories of your original 100g of dry oats remain the same.

No, when measured dry, steel-cut and rolled oats have very similar calorie counts and nutritional profiles. The main differences are in their processing, texture, and the rate at which they are digested, not their base calories.

Yes, eating oats daily can aid in weight loss, provided you control your portion sizes and toppings. The high fiber content promotes a feeling of fullness, which can help reduce overall calorie intake throughout the day.

Using milk instead of water significantly increases the calorie count. For example, 1 cup of 2% milk adds about 120 calories, while unsweetened almond milk adds only about 30 calories per cup. The total depends on the type and quantity of milk used.

Instant oatmeal retains most of its core nutritional value, but it has a higher glycemic index than steel-cut or rolled oats, causing a faster blood sugar spike. Furthermore, pre-packaged, flavored instant oats often contain high amounts of added sugar, which can be detrimental to health goals.

To reduce calories, prepare your oats with water or low-calorie milk alternatives like unsweetened almond milk. Opt for naturally sweet additions like berries or cinnamon instead of added sugars or high-calorie toppings.