[@The Mad Hatter] LMAO well as the Hatter I would imagine it would be odd seeing as you have so many cups to choose from but let me see if I can help. American Standard of a cup is 8 ounces in weight or volume. When it comes to things such as cooking when one says a cup they mean 8 ounces by volume, not weight. A cup of flour can vary widely in weight depending on how much you pack it down while a cup of granulated sugar tends to be even. Now, when measuring flour in a recipe that uses cups fluff the flour then spoon it in and level off for more consistent outcomes. Or if you can, find a recipe that calls for weight of flour instead, this will result in the best outcome. (I have provided both as weight is best but most don't have a kitchen scale.) I hope this helps and I am not just Stark Raving Mad.