Graham flour is a type of flour made from wheat in accordance with the designs of American religious minister Sylvester Graham. It is a special variation of whole wheat flour, made by mixing finely milled white flour with coarsely milled bran and wheatgerm, in the proportions that they would be found in a whole wheat berry.
Rather than simply grinding the whole grain wheat kernel (bran, germ, and endosperm), in graham flour the components are ground separately. The endosperm is ground finely, initially creating white flour. The bran and germ are ground coarsely. The two parts are then mixed back together, creating a coarse-textured flour that bakes and keeps well. Graham flour is used to make graham crackers and pie crusts, among other things.
Graham flour is not available in all countries. A fully correct substitute for it would be a mix of white flour, wheat bran, and wheat germ in the ratio found in whole wheat. Wheat comprises approximately 83% endosperm, 14.5% bran, and 2.5% germ by mass. For sifted all-purpose white flour, wheat bran, and wheat germ having densities of 125, 50, and 80 grams/cup, respectively, one cup of graham flour is approximately equivalent to 84 g (~2/3 cup) white flour, 15 g (slightly less than 1/3 cup) wheat bran, and 2.5 g (1.5 teaspoons) wheat germ.
Plain whole wheat flour can also be used as a substitute in recipes, but the texture of the resulting baked goods will be different than if graham flour had been used.