24 oz (or 4.25 Cups) Superfine Brown Rice Flour
24 oz (or 4.25 Cups) Superfine White Rice Four
24 oz (or 4.25 Cups) Sweet Rice Flour
20 oz (or 4.5 Cups)Tapioca Flour
0.8 oz (2½ Tablespoons) Xanthan Gum* (optional; see note below)
If you have a kitchen scale, weighing the ingredients is the more accurate option. You will need a very large bowl and will need to whisk the flours together for several minutes to achieve a homogeneous mixture. Store in an airtight container or freezer bag.
*Xanthan gum is not necessary for successful quick breads, waffles, and brownies, but it does act as a binder for leavened breads (both yeast breads and those that are chemically leavened), giving them a more springy, chewy texture. For every cup of gluten-free flour blend used in leavened breadmaking, you'll need about 1/2 teaspoon xanthan gum.