Amaranth flour

One US cup of amaranth flour weighs between 103 and 140 grams, depending on how the cup is filled and which source measured it. That range is the answer; a single number would not be. Every figure behind it is below, with the method each source used.

Also called amaranth flour, whole grain amaranth flour, rajgira atta, rajgira flour, amaranth pseudocereal flour.

Amaranth flour publishes as a range 103 to 140 grams per cup because two authoritative sources disagree by 26%, well over the 10% milled tolerance, and the disagreement reflects real milling variance between different commercial amaranth flour products.

King Arthur publishes 103 g/cup for amaranth flour (density 0.4354 g/mL), representing a lighter finely-milled or sifted product. Bob's Red Mill Whole Grain Amaranth Flour publishes 35 grams per 1/4 cup on its nutrition label, back-calculating to 140 g/cup (density 0.5918 g/mL). The 35 g figure is notable because it does not match the FDA Reference Amount Customarily Consumed default of 30 g for flour, suggesting Bob's measured this specific product rather than defaulting to a labeling standard. The 37-gram spread across the range reflects genuine product-milling variance.

Amaranth is a pseudocereal, not a true cereal grain. It comes from plants in the genus Amaranthus and has been cultivated for grain for 8,000 years, particularly in Mesoamerica and India. The tiny seeds (about 1 mm across) mill differently than wheat because they contain higher protein (14 percent) and higher fat (7 percent) than typical cereal grains, plus a different bran structure. Amaranth flour is naturally gluten-free and is used in traditional Indian rajgira atta preparations for religious fasting periods, in Mexican pinole and atole beverages, and in modern gluten-free baking as a nutrient-dense alternative to wheat flour.

Physical mechanism for the density spread: stone-ground whole-grain amaranth flour (Bob's Red Mill) retains more of the grain's original structure, including denser bran fragments and starch-protein complexes that pack tightly. Fine-milled or sifted amaranth flour (matching KA's reference) has been processed further, breaking down these structures and creating a lighter, airier flour. The physical difference is analogous to whole wheat flour versus sifted whole wheat pastry flour, though the density gap for amaranth is larger because amaranth's tiny seed geometry creates more variability in what milled means across producers.

USDA FoodData Central added a Foundation Foods entry 'Flour, amaranth' in April 2023 (Version 9.1 update), but published cup portions are not consistently available. USDA does publish 'Amaranth grain, uncooked' at FDC 170682 with a direct cup portion of 193 g/cup — this is the whole intact grain, not the flour, and reflects the denser packing of unbroken tiny seeds versus milled powder. Any recipe that specifies amaranth by cup should clarify whether it means whole grain (193 g/cup) or flour (103-140 g/cup depending on milling), since the two are physically distinct ingredients with very different weights.

Compared to other flours on the site, amaranth flour at 103-140 g/cup brackets the wheat flour cluster: 103 sits below all-purpose (120) and above whole wheat pastry (96), while 140 sits above all wheat flours. The wide range reflects amaranth's unusual pseudocereal seed structure and the significant impact of milling method on the final flour density. Quinoa flour and other pseudocereal flours show similar variance for the same reasons.

Category assignment is milled, matching all other flours on the site.

Confidence is low reflecting the 26% gap between authoritative sources. For baking accuracy, weigh amaranth flour rather than measuring by volume. If a recipe was developed against KA references or a sifted amaranth flour, use 103 g/cup. If developed against Bob's Red Mill or another whole-grain stone-ground amaranth flour, use 140 g/cup. If in doubt, use 120 g/cup as a middle estimate. This entry represents a moat play for the site: no other cup-to-gram reference publishes the KA versus Bob's amaranth flour gap with the physical explanation that stone-ground whole-grain milling produces a denser flour than fine-milled or sifted references, and no other reference distinguishes amaranth's flour density from its whole grain density transparently.