Buckwheat is a non-wheat flour that is often used by people who cannot eat gluten. Its strong flavor and pleasing texture makes it a favorite for pancakes. Because it lacks gluten, it is used in non-leavened baked goods such as crackers. Other strongly flavored non-wheat flours, and even whole wheat flour, make a good substitution in recipes calling for buckwheat flour.
If gluten isn't an issue, wheat flour can be substituted on a one-to-one basis for buckwheat flour. If you think you'll miss buckwheat's flavor, consider mixing wheat flour with quinoa or ground flax and use the mixture in the recipe. Wheat flour behaves differently than non-wheat flour in baked goods, and if you're making bread you may need to knead the dough if you make this substitution.
Quinoa, like buckwheat, is an ancient grain that is often made into flour. These flours can be substituted one-to-one in buckwheat recipes. The strong flavor of quinoa often works well in recipes that call for the equally strong taste of buckwheat. Quinoa is high in protein and will boost the nutrition in the dish as well.
Other Non-wheat Flours
Although they will change the taste of the finished recipe, other flours can be substituted for buckwheat. Millet and oat flours are mild tasting and can be substituted one-for-one in recipes for unleavened buckwheat products. Rice flour is another mild non-wheat flour that will substitute for buckwheat.