For the conversion, 1 cup is typically equal to 8 ounces, so 1 and 1/3 cups would be 1.33 times that, which is around 10.67 ounces. When measuring liquids, it's best to use a liquid measuring cup and place it on a flat surface to get an accurate reading, and for dry ingredients, use a dry measuring cup and scoop or spoon the ingredients into it, then level it off with a straight edge to ensure you're getting the right amount, this way you can avoid over or under measuring and get the best results for your recipe.