Rolled Oats (old fashioned): Grams to Cups
1 cup of rolled oats (old fashioned) = 90 grams
One US cup of rolled oats (old fashioned) weighs 90 grams. One 250 ml metric cup — the one used in the UK, Australia, New Zealand and Canada — holds 95 grams. To convert any weight, divide the grams by the figure for your cup.
Old-fashioned rolled oats weigh about 90 g per cup — King Arthur Baking lists 89 g and USDA FoodData Central 81 g. Oats are flat flakes that stack loosely, so how firmly the cup is filled matters.
Rolled, quick and steel-cut
Rolled oats are whole groats steamed and pressed flat. Quick oats are the same flakes cut smaller, which lets them settle a little differently; King Arthur weighs old-fashioned and quick oats the same at 89 g per cup, and this site uses 85 g for quick oats. Steel-cut oats are chopped groats that have not been flattened — they are dense like rice, about 140 g per cup (King Arthur).
Because the flakes do not pack, do not press them into the cup; spoon or pour them in and level the top.
Cooked oats
½ cup (45 g) of rolled oats cooked with 1 cup of water makes about 1 cup of porridge. Cooked oatmeal is mostly water: USDA puts a cup of oats cooked in water at about 234 g.
Common oat amounts in cups: 45 g, 90 g, 100 g and more
At 90 g per cup the arithmetic is unusually friendly: 45 g is ½ cup, 60 g is ⅔ cup, 90 g is exactly 1 cup, 120 g is 1⅓ cups, 180 g is 2 cups and 270 g is 3 cups.
The amounts that do not land on a neat fraction: 100 g of rolled oats is 1 cup plus about 2 tablespoons (1.11 cups), 200 g is about 2¼ cups, 250 g is about 2¾ cups and 500 g is about 5½ cups. One tablespoon of rolled oats weighs about 5.6 g.
If your oats are quick oats, use 85 g per cup instead; 90 g of quick oats is a little over 1 cup.
Oats in baking
In cookies and crumbles, old-fashioned and quick oats are usually interchangeable by weight, but not always by feel: quick oats give a finer, more uniform texture, old-fashioned a chewier one. Do not swap steel-cut oats for either — they stay hard in the time a cookie bakes. For oat flour, blend rolled oats: 90 g of oats makes about 90 g of flour.
Where the 90 g figure comes from
- USDA FoodData Central: 1 cup of “Cereals, oats, regular and quick, not fortified, dry” = 81 g (FDC ID 173904)
- King Arthur Baking ingredient weight chart: Oats (old-fashioned or quick-cooking), 1 cup = 89 g (chart)
This site uses 90 g per US cup of rolled oats (old fashioned), spooned and levelled. References checked September 2026.
How many cups is X grams of rolled oats (old fashioned)?
| Grams | US cups | Metric cups | Tablespoons | Ounces |
|---|---|---|---|---|
| 25 g rolled oats (old fashioned) | ¼ | ¼ | 4.44 | 0.88 |
| 50 g rolled oats (old fashioned) | ½ | ½ | 8.89 | 1.76 |
| 75 g rolled oats (old fashioned) | ⅞ | ¾ | 13.33 | 2.65 |
| 100 g rolled oats (old fashioned) | 1⅛ | 1.05 | 17.78 | 3.53 |
| 110 g rolled oats (old fashioned) | 1¼ | 1⅛ | 19.56 | 3.88 |
| 120 g rolled oats (old fashioned) | 1⅓ | 1¼ | 21.33 | 4.23 |
| 125 g rolled oats (old fashioned) | 1⅜ | 1⅓ | 22.22 | 4.41 |
| 130 g rolled oats (old fashioned) | 1½ | 1⅜ | 23.11 | 4.59 |
| 140 g rolled oats (old fashioned) | 1½ | 1½ | 24.89 | 4.94 |
| 150 g rolled oats (old fashioned) | 1⅔ | 1⅝ | 26.67 | 5.29 |
| 170 g rolled oats (old fashioned) | 1⅞ | 1¾ | 30.22 | 6.00 |
| 175 g rolled oats (old fashioned) | 1.94 | 1⅞ | 31.11 | 6.17 |
| 200 g rolled oats (old fashioned) | 2¼ | 2⅛ | 35.56 | 7.05 |
| 225 g rolled oats (old fashioned) | 2½ | 2⅜ | 40 | 7.94 |
| 240 g rolled oats (old fashioned) | 2⅔ | 2½ | 42.67 | 8.47 |
| 250 g rolled oats (old fashioned) | 2¾ | 2⅝ | 44.44 | 8.82 |
| 275 g rolled oats (old fashioned) | 3.06 | 2⅞ | 48.89 | 9.70 |
| 300 g rolled oats (old fashioned) | 3⅓ | 3⅛ | 53.33 | 10.58 |
| 350 g rolled oats (old fashioned) | 3⅞ | 3⅔ | 62.22 | 12.35 |
| 400 g rolled oats (old fashioned) | 4½ | 4¼ | 71.11 | 14.11 |
| 450 g rolled oats (old fashioned) | 5 | 4¾ | 80 | 15.87 |
| 500 g rolled oats (old fashioned) | 5½ | 5¼ | 88.89 | 17.64 |
How to measure rolled oats (old fashioned) accurately
The 90 g figure assumes the spooned-and-levelled method: spoon the rolled oats (old fashioned) into a dry measuring cup and sweep the top flat with a straight edge. Scooping the cup through the bag compacts it and gives a heavier cup.
- 1 US cup of rolled oats (old fashioned) = 90 g
- 1 metric cup (250 ml) of rolled oats (old fashioned) = 95 g
- ¾ cup = 68 g
- ½ cup = 45 g
- ⅓ cup = 30 g
- ¼ cup = 23 g
- 1 tablespoon = 5.6 g
Frequently asked questions
How many cups is 100 grams of rolled oats (old fashioned)?
100 grams of rolled oats (old fashioned) is about 1⅛ US cups, based on 90 g per cup, or 1.05 metric cups.
How many grams in a cup of rolled oats (old fashioned)?
One US cup of rolled oats (old fashioned) weighs 90 grams. A 250 ml metric cup holds 95 grams.
How many cups is 250 grams of rolled oats (old fashioned)?
250 grams of rolled oats (old fashioned) is about 2¾ US cups, or 2⅝ metric cups.
Does a UK cup of rolled oats (old fashioned) weigh the same as a US cup?
No. A UK, Australian or Canadian metric cup is 250 ml against the US 236.6 ml, so it holds about 5.7% more — 95 g of rolled oats (old fashioned) rather than 90 g.
How many tablespoons is 100 grams of rolled oats (old fashioned)?
100 grams of rolled oats (old fashioned) is about 17.78 tablespoons.
How many cups is 90 grams of oats?
Exactly 1 cup of old-fashioned rolled oats, which weigh 90 g per cup when spooned in and levelled.
How many cups is 120 grams of oats?
1⅓ cups of old-fashioned rolled oats, because 120 ÷ 90 = 1.33. 100 g is 1 cup plus about 2 tablespoons.
How many grams is ½ cup of rolled oats?
45 grams, half of the 90 g in a full cup. Cooked with 1 cup of water it makes about 1 cup of porridge.
How many cups is 150 grams of oats?
About 1⅔ cups of rolled oats (150 ÷ 90 = 1.67).
How many cups is 400 grams of oats?
Just under 4½ cups of rolled oats (400 ÷ 90 = 4.44).