If you've looked online for a gluten-free recipe, you've probably run into this dilemma: you want to make something now, but you don't have - or can't get - one of the flours your delicious-looking recipe calls for. This quick guide is a reference for what kind of flour to substitute for what you're missing.
Keep in mind a few things when you substitute flours in a recipe: first, do it by weight if that is possible. A digital kitchen scale will make your life so much easier! Different flours measure very differently in measuring cups sometimes. Second, any substitution will change the texture and density of the dough. Thirdly, if you don't see the flour here that you want to substitute, try thinking of something with a similar fiber content and texture, and experiment. Starches can almost always be subbed out for other starches, and whole grain flours can replace each other, but don't sub a starch for a whole grain. Then let me know what you come up with!
brown rice flour - teff flour
white rice flour - finely-ground corn flour
corn meal - buckwheat
buckwheat - teff flour
sorghum flour - amaranth flour
tapioca starch - potato starch
arrowroot starch - corn starch
potato flour - millet flour
coconut flour - do not sub out! Coconut flour has much more fiber than anything else. If you substitute it, your ratio of flour to liquids will be completely thrown off. (Flours high in fiber call for more liquid.)
Do you have a favorite flour substitution? Let me know in the comments!