There are 14 net grams of carbohydrates in each 1/2 cup serving of cooked oatmeal. The same serving size also has 2 grams of fiber, 3 grams of protein and 83 calories. Steel-cut oatmeal has slightly more carbs with 1/4 cup of uncooked steel-cut oats having 24 net carbs.
Oat bran has slightly fewer carbs with 10 net grams in a 1/2-cup cooked portion. A 1/2-cup serving also contains 3 grams of fiber, 3 grams of protein and 44 calories. When preparing oatmeal, it is important to note that carb counts for instant oatmeal can be significantly higher because this type of oatmeal generally contains sugar and flavorings.