Rolled Oats — Grams & Cups Converter
1 cup of rolled oats (also called oats, porridge oats, old-fashioned oats) weighs about 90 g. Half a cup is 45 g, a tablespoon about 5.63 g, and a full cup is 3.17 ounces on a scale.
💡 Tip: Rolled oats are chewier than quick oats and swap 1:1 in most recipes, though quick oats absorb liquid faster and cook softer.
How many cups is a given weight of rolled oats?
| Grams | Amount | Ounces |
|---|---|---|
| 50 | 1/2 cup | 1.76 |
| 100 | 1 1/8 cups | 3.53 |
| 150 | 1 2/3 cups | 5.29 |
| 180 | 2 cups | 6.35 |
| 200 | 2 1/4 cups | 7.05 |
| 250 | 2 3/4 cups | 8.82 |
| 300 | 3 1/3 cups | 10.6 |
| 400 | 4 1/2 cups | 14.1 |
| 500 | 5 1/2 cups | 17.6 |
| 750 | 8 1/3 cups | 26.5 |
| 1000 | 11 1/8 cups | 35.3 |
Why oats weigh so little (and serving sizes)
Rolled oats are airy flakes, so a cup is only about 90g — one of the lightest dry ingredients in the kitchen. That makes weighing especially worthwhile, since a loosely or firmly filled cup can vary a lot. A standard dry serving is 40g, roughly ½ cup.
Rolled and quick oats weigh the same per cup and swap 1:1; quick oats simply cook faster and give a softer texture. Steel-cut oats are denser and are not a cup-for-cup substitute, so convert those by weight.
From cups to grams: rolled oats
| Cups | Grams | Ounces |
|---|---|---|
| 1/4 | 22.5 | 0.79 |
| 1/3 | 30 | 1.06 |
| 1/2 | 45 | 1.59 |
| 3/4 | 67.5 | 2.38 |
| 1 | 90 | 3.17 |
| 1 1/2 | 135 | 4.76 |
| 2 | 180 | 6.35 |
| 3 | 270 | 9.52 |
| 4 | 360 | 12.7 |
There are 16 tablespoons in a cup, so one tablespoon of rolled oats weighs roughly 5.63 g — and a teaspoon 1.88 g.
Where rolled oats sits by weight
A cup of rolled oats weighs 90 g, which puts it 2nd by weight among the 17 grains & legumes on this site. Its nearest neighbours are quick oats at 80 g and frozen peas at 134 g per cup.
Swapping these by the cupful is not like-for-like. A cup of frozen peas in place of rolled oats puts roughly 44 g more in the bowl, so match the grams rather than the cups.
Questions people ask about rolled oats
- How many cups is 100g of rolled oats?
- Just over or under 1 1/8 cups, depending how firmly you fill the cup. 100 g ÷ 90 g per cup = 1 1/8 cups.
- How many grams is 1 cup of rolled oats?
- 1 cup of rolled oats is about 90g (3.2 ounces), and 2 cups is 180g. Oats are light because the flakes trap a lot of air.
- How many grams is a serving of oats?
- A typical dry serving is 40g, which is about ½ cup of rolled oats.
- Why is a cup of oats so light?
- Rolled oats are flattened flakes that stack loosely with lots of air between them, so a cup holds only about 90g — far less than a cup of flour or sugar.
- Do rolled oats and quick oats weigh the same?
- Yes, both are about 90g per cup. Quick oats are just rolled thinner and cut smaller, so they cook faster and absorb liquid quicker, but the weight per cup is the same.
- How many cups is 50g of oats?
- 50g of rolled oats is a generous ½ cup (about 0.56 cups).
- How many cups is 200g of rolled oats?
- About 2 1/4 cups — that is 200 divided by the 90 g a cup weighs.
- Why do my numbers differ slightly?
- Grain size and moisture vary by variety and age. Long thin grains stack with more air between them than short round ones, and older, drier stock weighs a little less per cup.