The carbs in grilled cheese sandwiches will vary, depending on what type of bread and cheese you use. The average grilled cheese will have around 500 calories and over 30 total carbs. When using white bread, net carbs are almost just as high, since white bread doesn't have much fiber.
In this keto grilled cheese recipe, the calories are a little higher as the bread is made with nutrient-dense almond flour... and the carbs are much, much lower. Just 4.9 grams net carbs for the whole sandwich!