I couldn’t find graham flour at my local Whole Foods. The people in the store didn't even know what I was talking about!! I remembered an Alton Brown Good Eats' episode where he told the ratios for making your own graham flour. The internet is handy for finding such information when you need it.
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[1]. 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.
