Flax meal

One US cup of flax meal weighs between 100 and 112 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 ground flaxseed, ground flax seeds, flaxseed meal, milled flaxseed, linseed meal, ground linseed.

Two authoritative sources disagree by 12%, just over the 10% milled tolerance. King Arthur's Ingredient Weight Chart publishes 1/2 cup at 50 g (extrapolating to 100 g per cup, 0.4227 g/mL). USDA FoodData Central and multiple commercial brands converge on 7 g per tablespoon, extrapolating to 112 g per cup (0.4734 g/mL). The gap is small but consistent across multiple brands aligning with USDA, so this entry publishes the range rather than choosing one figure.

Ground flaxseed (also called flax meal or flaxseed meal) is a fine oily powder produced by grinding whole flax seeds. The oil content is high (approximately 42% of the seed by weight is oil), which makes ground flax pack differently than dry powders like wheat flour. The oily coating on each particle causes slight clumping that responds to scoop-and-shake versus spoon-and-level techniques, producing the small but real density variation between sources. King Arthur likely measures a fluffier spoon-and-level fill; the brand consensus at 112 g per cup reflects the standard nutrition-label serving that assumes a settled measure.

Ground flaxseed is a common vegan egg substitute: 1 tablespoon of ground flax (approximately 7 g) mixed with 3 tablespoons of water and left for 5 minutes forms a gel that binds baked goods similarly to a single chicken egg. The substitution ratio depends on getting the flax weight right, which is why weighing is preferable to volume measurement for this use.

Whole flaxseed is a distinct product measured separately on this site's forthcoming whole-flaxseed entry. King Arthur lists whole flaxseed at 35 g per 1/4 cup, extrapolating to 140 g per cup, roughly 40% denser than the ground form. The density difference is not a measurement error: whole seeds pack tightly with minimal air space between the smooth oval shapes, while ground meal has more air space in the powder matrix. The distinction matters because whole flaxseeds pass through the digestive system largely intact due to their hard outer hull; only ground flax delivers the omega-3 fatty acids (alpha-linolenic acid) and lignans that make flax nutritionally significant.

Golden flaxseed and brown flaxseed have the same density and identical omega-3 content. Golden flax has a milder flavor and is preferred for light-colored baked goods; brown flax is more traditional. Both are Linum usitatissimum, the same species.

Storage matters for accuracy over time. Ground flaxseed's high oil content and increased surface area from grinding cause it to oxidize rapidly at room temperature, developing a rancid flavor within weeks. Commercially packaged flax meal typically includes antioxidants or nitrogen-flushed packaging to slow this; once opened, refrigeration or freezer storage is required. Freshly-ground flax from a spice grinder is optimal but must be used within days. Rancidity does not significantly affect the density, but it does affect the flavor of finished baked goods and reduces the omega-3 bioactivity.

Flax meal sits in the milled category alongside flours and other ground powders. The 10% category tolerance applies here, and the observed 12% gap between authoritative sources is just outside it, warranting the range publish rather than a single figure.

Related products: whole flaxseed (denser at approximately 140-150 g per cup, separate entry planned), flaxseed oil (a distinct product in the fat category, not covered here), chia seed (a nutritionally similar seed sometimes substituted for flax in vegan egg preparations, but with different density). Linseed is the British and European name for flaxseed; the two terms refer to the same seed.

No standards body publishes a bulk density for ground flaxseed. Codex Alimentarius has no dedicated flax standard. Two authoritative sources with a small but consistent gap, so this entry is held at low confidence and range published until a third independent source resolves the disagreement.