I will answer this question in two parts. First, not all casserole dishes that are 3 quartz have a dimension of 9 X 13 inches in size.  For example, the oxo good grips freezer to oven safe 3 qt glass baking dish WITH LID IS 9 X 13” INCHES.The Pyrex 3 QT Glass Baking dish with Blue Cover is 9 X 13” inches,  also the Anchor Hocking 3 Quart Glass Baking Dish with Teal Truefit Lid is 13 X 9 “ inches and the Emile Henry Made In France HR Modern Classic Large Rectangular Baker is 13 X 9 “ inches white Casserole dish with an internal dimension of 11.15 inch by 8.25 inch, height is 2.5 inches.While the Anolon 51032 Vesta Ceramics AU Gratin and Creo SmartGlass Cookware Baking Dish are both 3 Quart but have different sizes, the first is 19 X 13 X 4.5 inches, the other is 12.4 X 9 X 2.25” inches.