One 100 g serving of mcdonald's, egg mcmuffin has 228 calories, 21.7 g of carbs, and 1.1 g of fiber.
Full macro and micronutrient breakdown, plus how this compares across diets, is on the McDONALD'S, Egg McMUFFIN nutrition facts page.
Source: USDA FoodData Central - SR Legacy (2018-04)