Ounces of rolled oats to cups runs on one number, 0.3149947 cups per ounce. It is a measured property of this ingredient rather than a defined conversion, which is why a generic volume-to-weight tool cannot give you it.
The density behind that figure is 0.38041 g per mL, against 1.00 for water. A cup of water weighs 236.6 g and a cup of rolled oats weighs 90 g, so this ingredient is 38.04% as heavy as the same volume of water — the single fact the whole page rests on.
A cup of rolled oats is 90 g when it is measured the standard way, but how it gets into the cup changes the answer: between about 81 g and 108 g covers the range from lightly spooned to firmly packed. That 20% spread is larger than most of the adjustments recipes fuss over, and it disappears entirely the moment the ingredient is weighed instead.
One cup of rolled oats is 3.175 oz. US kitchen scales usually step in eighths of an ounce, which is 3.54 g — around 3.94% of a cup of this ingredient, so the scale is precise enough for a full cup and coarse for a spoonful. That is why recipes mix the two systems: ounces for the bulk, spoons for the small amounts.
How the figure is arrived at: Old-fashioned flakes. Very light for their volume because of the air trapped between them.
The formula
ounces- The amount of rolled oats you are converting, in ounces
0.314994701389- Cups per ounce for rolled oats, from its density of 0.38041 g/mL
cups- The equivalent quantity in cups
How it works, step by step
- Enter the quantity in ounces.
- It is multiplied by 0.314994701389, the cups-per-ounce figure for rolled oats.
- The result appears in cups, with a second reading in tbsp beneath it.
- Use the measure table if you want a standard recipe quantity rather than a number you type in.
Worked examples
2 oz of rolled oats in cups
2 oz of rolled oats weighs out at 0.629989 cups. Divide 0.629989 by 0.3149947 and you get back to 2 oz, which is the quickest check that the factor is the right way up.
4 oz of rolled oats in cups
Take 4 oz of rolled oats: 4 × 0.3149947 gives 1.25998 cups. Doubling the batch takes it to 2.51996 cups, because the relationship is a straight proportion once the density is known.
12 oz of rolled oats in cups
A recipe calling for 12 oz of rolled oats needs 3.77994 cups on the scale. The arithmetic is 12 × 0.3149947 = 3.7799364, and halving the recipe halves the weight to 1.88997 cups.
How to read your score
Frequently asked questions
How many cups are in 1 oz of rolled oats?
One ounce of rolled oats is 0.3149947 cups. Half that quantity is 0.157497 cups and double it is 0.629989 cups, so the figure scales straight up and down — there is no offset in this conversion, only the factor.
Why is a cup of rolled oats not 236 g like water?
Because weight per cup depends on what is in the cup. Rolled oats has a density of 0.38041 g per mL where water has 1.00, so a cup of it weighs 90 g rather than 236.6 g. That is a difference of 146.6 g per cup, and it is the reason a single volume-to-weight factor cannot be applied to every ingredient.
Does how I measure it change the weight?
Yes, and by more than most people expect. Handling changes the weight of a cup of rolled oats by roughly 20% — about 9 g either side of 90 g — because old-fashioned flakes. Weighing removes the question entirely.
Is a fluid ounce of rolled oats the same as an ounce?
No. A fluid ounce is a volume — one eighth of a US cup, 29.57 mL — and an ounce is a weight. One fluid ounce of rolled oats weighs 0.3968 oz, so the two readings differ by 60.3%. They coincide only for something with the density of water, and then only roughly.
Is this a US cup or a metric cup?
US customary: 236.59 mL, which is the cup every US recipe means. A metric cup is 250 mL, so the same cup of rolled oats would weigh 95.102 g instead of 90 g — 5.1 g more, or 5.67%. Australian and some European recipes use the metric cup, and the difference is large enough to matter in baking.
Do I need a scale for this, or will measuring cups do?
A scale, if the result matters. Volume measuring carries a spread of about 20% for rolled oats — roughly 18 g on a 90 g cup — while a domestic scale is accurate to a gram or two. For anything where the ratio of ingredients drives the outcome, bread and pastry above all, weigh it.
How much does 2 cup of rolled oats weigh?
2 cup of rolled oats comes to 180 g, or 6.3493 ounces. This page runs that calculation in reverse — enter a weight and it returns the volume — and the cups-to-ounces page does it in the direction the question is usually asked.
Rolled oats in ounces and cups
| Ounces | Cups | Unrounded |
|---|---|---|
| 1/2 oz | 0.157497 cup | 0.1574973507 |
| 1 oz | 0.314995 cup | 0.3149947014 |
| 2 oz | 0.629989 cup | 0.6299894028 |
| 3 oz | 0.944984 cup | 0.9449841042 |
| 4 oz | 1.25998 cup | 1.259978806 |
| 6 oz | 1.88997 cup | 1.889968208 |
| 8 oz | 2.51996 cup | 2.519957611 |
| 12 oz | 3.77994 cup | 3.779936417 |
| 16 oz | 5.03992 cup | 5.039915222 |
Based on 90 g per cup of rolled oats. One ounce of rolled oats is 0.3149947 cups.
| Measure | Grams | Ounces | Millilitres |
|---|---|---|---|
| 1 cup | 90 g | 3.17 oz | 236.6 mL |
| 3/4 cup | 67.5 g | 2.38 oz | 177.4 mL |
| 2/3 cup | 60 g | 2.12 oz | 157.7 mL |
| 1/2 cup | 45 g | 1.59 oz | 118.3 mL |
| 1/3 cup | 30 g | 1.06 oz | 78.86 mL |
| 1/4 cup | 22.5 g | 0.794 oz | 59.15 mL |
| 1 tbsp | 5.625 g | 0.198 oz | 14.79 mL |
| 1 tsp | 1.875 g | 0.0661 oz | 4.929 mL |
US customary measures: 1 cup = 236.59 mL, 1 tbsp = 14.79 mL, 1 tsp = 4.93 mL.
| Ingredient | Grams per cup | Ounces per cup | Density (g/mL) |
|---|---|---|---|
| Panko breadcrumbs | 60 g | 2.116 oz | 0.2536 |
| Cocoa powder | 85 g | 2.998 oz | 0.3593 |
| Rolled oats (this page) | 90 g | 3.175 oz | 0.3804 |
| Oat flour | 92 g | 3.245 oz | 0.3889 |
| Almond flour | 96 g | 3.386 oz | 0.4058 |
| Rye flour | 102 g | 3.598 oz | 0.4311 |
| Dry breadcrumbs | 108 g | 3.81 oz | 0.4565 |
Ordered by weight. The spread across this group is why a single generic cups-to-grams factor cannot work.