Oats: grams to cups
1 cup of rolled oats, old-fashioned or quick-cooking, weighs 89 grams, so 100 g of oats is 1.12 cups, about 1⅛ cups.
Oats are light for their bulk: a whole cup weighs less than half a cup of granulated sugar (99 g). Half a cup of oats, a common single portion for oatmeal, is about 45 g.
Converter
Measure it as 1 cup + 2 tbsp.
| Volume | Grams | Ounces |
|---|---|---|
| 1 tbsp | 5.6 g | 0.2 oz |
| ¼ cup | 22.3 g | 0.8 oz |
| ⅓ cup | 29.7 g | 1 oz |
| ½ cup | 44.5 g | 1.6 oz |
| ⅔ cup | 59.3 g | 2.1 oz |
| ¾ cup | 66.8 g | 2.4 oz |
| 1 cup | 89 g | 3.1 oz |
| 2 cups | 178 g | 6.3 oz |
| Grams | US cups | Measure it as |
|---|---|---|
| 40 g | 0.45 | ¼ cup + 3 tbsp + ½ tsp |
| 50 g | 0.56 | ½ cup + 1 tbsp |
| 80 g | 0.9 | ¾ cup + 2 tbsp + 1 tsp |
| 100 g | 1.12 | 1 cup + 2 tbsp |
| 150 g | 1.69 | 1⅔ cups + 1 tsp |
| 200 g | 2.25 | 2¼ cups |
| 250 g | 2.81 | 2¾ cups + 1 tbsp |
| 500 g | 5.62 | 5½ cups + 2 tbsp |
Weights from the King Arthur Baking ingredient weight chart, checked October 7, 2026. King Arthur Baking lists “Oats (old-fashioned or quick-cooking)” at 1 cup = 89 g. Grams per cup is worked out from their figure; ounces are converted from grams.
Old-fashioned, quick and steel-cut
Old-fashioned and quick oats weigh the same per cup in King Arthur's chart; quick oats are just rolled thinner and cut smaller. Steel-cut oats are chopped grains rather than flakes, so they pack far more densely and the weights here don't apply. Weigh them or follow the package.
Oat flour
Blitzing rolled oats in a blender makes oat flour. The weight stays the same but the volume shrinks, so if a recipe gives oat flour in grams, grind that same weight of oats. If it gives cups of oat flour, grind more than that many cups of oats and measure after.
Granola and cookies
In granola and oatmeal cookies, oats are the bulk of the dry mix. Weighing them keeps the ratio to butter and sugar steady, which is what decides whether granola clusters or cookies spread. The grams to cups chart has the other ingredients.
Overnight oats and granola recipes are all over TikTok and Instagram. ReelMeal saves them as written recipes, with the amounts listed and the creator's video linked.
Download on theApp StoreQuestions
How many grams is 1 cup of oats?
89 g of old-fashioned or quick rolled oats, per King Arthur Baking.
How many cups is 100 g of oats?
1.12 cups, a little more than 1 cup.
How many grams is ½ cup of oats?
About 45 g.
Do quick oats and rolled oats weigh the same?
Per cup, yes: King Arthur lists both at 89 g.