How Many Calories Are in 40gm of Oats? Your Full Nutrition Guide

December 10, 2025 •

4 min read

A standard 40-gram serving of dry oats contains approximately 150-156 calories. For those asking about “OTS,” this is a common abbreviation for oats, and the calorie count for this healthy grain is a key part of many balanced diets.

Quick Summary

An average 40-gram serving of plain, dry oats contains about 150 calories, with minimal nutritional variation between rolled, steel-cut, and instant types. The total calorie count depends on added ingredients.

Key Points

Standard Serving Calories: A 40gm serving of plain, dry oats contains approximately 150-156 calories, regardless of the type.
OTS is a Typo for Oats: The term 'OTS' is typically a user's mistake for 'oats,' a whole grain with documented health benefits.
Processing Doesn't Change Base Calories: The nutritional value per gram is nearly identical for steel-cut, rolled, and instant oats; the difference lies in processing, texture, and cooking time.
Preparation Affects Calorie Count: Adding milk, sweeteners, and high-calorie toppings can significantly increase the total calories of your oat meal.
Oats are Fiber-Rich: The grain is a great source of soluble fiber, particularly beta-glucan, which supports heart health, digestion, and blood sugar control.

What are the calories and macronutrients in 40gm of plain oats?

When considering how many calories are in 40gm OTS, it is first important to clarify that “OTS” is a common typo for “oats,” a widely consumed and nutritious whole grain. A standard serving of 40 grams of dry, uncooked oats—regardless of whether they are rolled, steel-cut, or instant—contains an average of 150-156 calories. The minimal processing differences do not substantially alter the core caloric value per gram. This serving provides a balanced mix of complex carbohydrates, protein, and dietary fiber, making it an excellent source of sustained energy. For a 40-gram serving, the approximate macronutrient breakdown is: around 27g of carbohydrates, 3g of fat, and 5-7g of protein.

The nutritional benefits of a 40g serving

Beyond the calorie count, a 40g serving of oats offers significant health benefits due to its rich nutrient profile. It is packed with fiber, notably a soluble fiber called beta-glucan, which is known for its ability to lower cholesterol and help regulate blood sugar levels. This makes oats a great food for heart health and for managing type 2 diabetes. The high fiber content also promotes satiety, helping you feel full for longer, which is beneficial for weight management. Furthermore, oats contain powerful antioxidants called avenanthramides that help reduce inflammation, and they are a good source of important minerals like manganese, phosphorus, and magnesium.

Comparison of Different Oat Types (Per 40g dry serving)

While the base nutritional values of plain oats are similar, the processing affects texture, cooking time, and glycemic index.


Feature	Rolled Oats (Old-Fashioned)	Steel-Cut Oats (Irish Oats)	Instant Oats (Quick Oats)
Processing	Steamed and flattened into flakes.	Whole oat groats cut into smaller pieces.	Thinned and cut into very small pieces.
Cooking Time	3-5 minutes on stove/microwave.	15-30 minutes, requires longer prep.	1-2 minutes in microwave or with hot water.
Texture	Softer, creamy texture.	Chewy, nutty, and firm.	Very soft, often mushy.
Calories (approx.)	150 kcal.	150 kcal.	148-150 kcal.
Carbohydrates (approx.)	27g.	27g.	27g.
Fiber (approx.)	4g.	4g.	4g.
Glycemic Index (GI)	Lower-medium GI (approx. 57).	Lower GI (approx. 53).	Higher GI (approx. 83).

The impact of preparation and toppings on calorie count

One of the most significant factors affecting the total calorie count of your oat meal is the way it is prepared and the ingredients added. A bowl of 40g oats with water has the base calorie count, but adding certain liquids or toppings can easily double or triple the total.

Preparing oats with different liquids

Water: The most calorie-conscious option. Cooking 40g of oats with water keeps the meal around its base calorie count of 150-156 kcal.
Milk (dairy): Using semi-skimmed milk will add a significant number of calories. For instance, 300ml of semi-skimmed milk could add an extra 141 kcal, bringing the total to around 291 kcal. Full-fat milk will add even more calories.
Plant-based milks: The calorie count varies greatly by type. A cup of almond milk is much lower in calories than a cup of oat milk, for example. Always check the nutrition label.

Adding common toppings

Sugars and sweeteners: A tablespoon of honey or maple syrup can easily add 60-70 calories. White or brown sugar also contributes empty calories.
Nut butters: A single tablespoon of peanut butter can add around 90-100 calories, plus healthy fats and protein.
Seeds: Flaxseeds, chia seeds, and pumpkin seeds are great for nutrients but also add calories. A tablespoon of chia seeds can add about 60 calories.
Nuts: Chopped almonds, walnuts, or pecans are calorie-dense. A small handful can add a substantial amount.
Fruit: Fresh berries are a low-calorie addition, while dried fruits like raisins and dates contain more concentrated sugar and calories.

Preparation method matters

Plain porridge: Cooked with water, this is the lowest-calorie option.
Overnight oats: Combining oats with milk, yogurt, and other mix-ins increases the calories, but allows for easy, ready-to-eat breakfasts.
Baked oats: Baked oat recipes often include additional ingredients like sugar, milk, and eggs, significantly increasing the calorie count.

Conclusion: A versatile and healthy grain

In summary, a 40-gram serving of plain, dry oats contains approximately 150 calories, with minimal differences between rolled, steel-cut, and instant varieties. The misconception of “OTS” is simply a common typo for this healthful grain. The real variable in total calorie intake comes from preparation and added ingredients like milk, sweeteners, nuts, and dried fruit. By choosing water or low-calorie milk alternatives and being mindful of toppings, you can enjoy a nutritious, low-calorie breakfast that supports heart health, digestion, and weight management. Oats are an incredibly versatile and healthy addition to any diet. For more detailed information on oat nutrition, consult a resource like Healthline.

Frequently Asked Questions

For a plain, dry 40g serving, the calorie difference is negligible. Both rolled and steel-cut oats contain approximately 150 calories per 40g, as the core nutritional content per weight is the same.

Adding milk increases the calorie count. For example, cooking 40g of oats with 300ml of semi-skimmed milk adds approximately 141 calories, bringing the total to around 291 kcal.

While instant oats have a higher glycemic index than rolled or steel-cut oats, they have the same nutritional profile per gram. To manage blood sugar spikes, you can pair them with protein- and fat-rich toppings like nuts and seeds.

The lowest-calorie method is to cook 40g of plain oats with water and use low-calorie toppings like fresh berries.

The act of cooking oats with water does not change their caloric value. However, cooking with liquids other than water, or adding ingredients, will alter the total calorie count.

Yes, oats can aid in weight loss. Their high fiber content, specifically beta-glucan, increases satiety, helping you feel full for longer and reducing overall calorie consumption.

Healthy toppings include fresh fruits, a small handful of nuts or seeds, a dash of cinnamon, or a small amount of Greek yogurt for added protein. These add nutrients without excessive calories.