They have a pretty decent nutritional guide[1] on their website, my usual was the salad bowl (big lettuce), no salad dressing, no rice, no beans, fajita veggies, double meat steak + barbacoa, the green salsa (has the fewest net carbs), sour cream, cheese, guac. That leaves you with this: http://imgur.com/WZBEczv, 14g net carbs (net carbs = carbs - fiber). My target was <30g per day. Breakfast gave almost 0, dinner would be 10-15g.

[1] http://www.chipotle.com/en-us/menu/nutrition_calculator/nutr...