Oat Flour: Cups to Grams

1 US cup of oat flour weighs about 92 grams.

Three quarters of a US cup of oat flour is about 69 grams (12 tablespoons).

2/3 of a US cup of oat flour is about 61.3 grams.

Half a US cup of oat flour is about 46 grams — half of the 92 g in a full cup.

A third of a US cup of oat flour is about 30.7 grams.

A quarter US cup of oat flour is about 23 grams (4 tablespoons).

1 tablespoon of oat flour is about 5.8 grams (a cup is 16 tablespoons).

1 1/4 US cups of oat flour weigh about 115 grams.

1 1/2 US cups of oat flour weigh about 138 grams — one full cup (92 g) plus half a cup (46 g).

2 US cups of oat flour weigh about 184 grams.

100 grams of oat flour is about 1.09 cups.

250 grams of oat flour is about 2.72 cups (at 92 g per cup).

500 grams of oat flour is about 5.43 cups.

Both are real measurements of a level US cup. King Arthur Baking's ingredient chart lists oat flour at 3 1/4 oz, or 92 g — the figure this page and its calculator use — while USDA's FoodData Central entry for oat flour (partially debranned, #169741) measures 104 g. The 13% gap is mostly how the cup was filled: King Arthur spoons flour lightly into the cup and levels it; a cup dipped into the bag packs oat flour down, because it is fluffy and compacts easily. Use 92 g for a recipe from a US baking site written in cups, and 104 g when working from a nutrition database.

Because three different cups are being converted. By King Arthur's chart (this page), 1 1/2 cups of oat flour is 138 g; by USDA's 104 g cup it is 156 g; and by the Bob's Red Mill or Quaker label serving of 1/4 cup = 30 g it is 180 g. King Arthur's own bag label (1/3 cup = 28 g) gives just 126 g. All describe a level US cup — labels are allowed to round, and dipped cups pack tighter than spooned ones. If the recipe was written in cups, 138 g is the safest reading; if it came with a gram weight, use the grams and ignore the cups.

A quarter US cup is 59.1 mL of volume, and that much oat flour weighs about 23 g (26 g by USDA's heavier cup). Millilitres measure space, not weight, so 59 mL of oat flour is 59 mL whatever it weighs; the grams are what change from ingredient to ingredient. The same 59 mL holds 30 g of all-purpose flour. Oat flour is about 38.9 g per 100 mL, so a 250 mL metric cup holds 97.2 g and a 200 mL glass 77.8 g.

100 mL of oat flour is about 38.9 g, and a level 250 mL metric cup — the standard in the UK, Australia and New Zealand — about 97.2 g (109.9 g by USDA's figure). A 236.6 mL US cup is 92 g, so a metric cup holds about 6% more; if a recipe from an Australian site says "1 cup oat flour", weigh 97.2 g rather than 92 g. Half a metric cup is 48.6 g.

Weigh 60 g of oat flour — the same weight as the half cup of all-purpose flour it replaces (60 g), which is about 0.65 cups, a scant 2/3 cup. A plain half cup of oat flour is only 46 g, 14 g short, because oat flour is about 23% lighter than wheat flour per cup. Quaker's guidance says the same thing by volume: 1 1/4 cups of oat flour for every cup of all-purpose, so 5/8 cup (10 tablespoons) for half a cup. Arrowhead Mills likewise says to swap by equal weight, not volume.

By weight, yes: Quaker's Oat Flour 101 guide states oat flour "can be substituted for all-purpose wheat flour at a 1:1 ratio by weight", and Arrowhead Mills says to use it "by equal weight instead of volume". By the cup, no — a cup of oat flour is 92 g against 120 g, so you need about 1 1/4 to 1 1/3 cups of oat flour per cup of all-purpose. The bigger limit is gluten: oat flour has none, so anything that has to rise needs wheat flour for structure. Quaker suggests swapping only about a third of the flour in bread; King Arthur says oat flour works for a portion of the flour in tender bakes like muffins, cakes and cookies, and its retail bag says up to half in non-yeasted recipes; Bob's Red Mill recommends adding xanthan gum when going fully gluten-free.

About 90 g of oat flour — grinding changes the volume, not the weight, so 90 g of rolled oats (1 cup) becomes 90 g of flour, which is very nearly 1 cup (92 g) of spooned oat flour by weight. None of the big mills publish a cup-for-cup yield, because freshly ground oats settle unevenly, so the reliable method is to weigh the oats before blending: for a recipe that wants 1 cup of oat flour, grind 92 g of rolled oats; for 1 1/2 cups, grind 138 g. King Arthur's recipes do exactly this — "1 1/2 cups (134 g) old-fashioned rolled oats, ground for 30 seconds in a blender".

Bob's Red Mill and Quaker both print 1/4 cup = 30 g, which is 120 g per cup; King Arthur's bag says 1/3 cup = 28 g (84 g per cup) and Arrowhead Mills and Gold Medal 1/3 cup = 30 g (90 g per cup). This page's chart gives 23 g for a quarter cup. The labels are not wrong — serving sizes are rounded to a convenient fraction and the nearest gram, and a dipped cup packs more than a spooned one — but they show why "1/4 cup" can mean anything from 21 to 30 g. For weighing, use 23 g; for counting calories, use the grams printed on your own bag.

About 372 kcal in a level cup (92 g), using USDA's 404 kcal per 100 g for oat flour. That cup also carries about 13.5 g of protein, 8.4 g of fat and 6 g of fiber. Half a cup is 186 kcal and a quarter cup 93 kcal. King Arthur's label agrees closely — 110 kcal per 28 g serving, about 393 per 100 g. A cup measured by USDA's heavier 104 g fill would be 420 kcal, which is one more reason to weigh rather than scoop when the numbers matter.

Oats contain no gluten, but ordinary oat flour is often not gluten-free in practice: the Celiac Disease Foundation notes that oats are commonly grown, processed and transported alongside wheat, barley and rye, and advises eating only oat products with a gluten-free label. Quaker's own guide states its oat flour is not certified gluten-free for that reason, while Bob's Red Mill mills its oat flour in a dedicated gluten-free facility and King Arthur's is certified by the GFCO. Certification changes nothing about the weight: certified and uncertified oat flour both weigh 92 g per spooned cup.

Nearly. A cup of rolled oats is about 90 g and a cup of oat flour 92 g on King Arthur's chart (89 g and 92 g on the chart itself; this site uses 90 g for oats) — grinding lets the flour fill the gaps between flakes, but the powder is so fluffy that it barely gains. Steel-cut oats are the outlier at about 160 g per cup, and oat bran sits near 94 g. So a recipe that swaps rolled oats for oat flour cup-for-cup is roughly right by weight, which is not true of the swap with wheat flour (120 g).

About 5.43 cups in 500 g and 10.87 cups in a kilogram, spooned and levelled at 92 g a cup — or 4.81 and 9.62 cups by USDA's 104 g fill. A 1 lb (454 g) bag holds about 4.93 cups, and King Arthur's 48 oz bag (1361 g) about 14.79 cups. Working backwards from a recipe, 100 g of oat flour is 1.09 cups and 200 g is 2.17 cups.