CupsToGrams kitchen card
1 US cup = 240 ml, 1 tablespoon = 15 ml, 1 teaspoon = 5 ml. Figures verified 5 August 2026. https://cupsngrams.com/cornstarch
Cornstarch: Cups to Grams
Also called cornflour or corn flour.
One US cup (240 ml) of cornstarch weighs 128 grams; half a cup weighs 64 grams. A quarter cup is 32 grams, a tablespoon is 8 grams and a teaspoon is 2.67 grams. A cup measures volume, not weight, so these numbers are for cornstarch only: a cup of honey weighs 340 grams.
128 g
1 cup of cornstarch = 128 g (US legal cup, 240 ml)
1 cup of cornstarch = 128 g (US legal cup, 240 ml)
Based on cornstarch at 128 g per US cup.
CupsToGrams, cupsngrams.com
Baking from a UK, Australian or New Zealand recipe? Their cup is not the American one. Pick the standard your recipe assumes and every cup figure follows it.
Cornstarch conversion table
| Cups | Cups (decimal) | Grams | Tablespoons | Millilitres | Ounces (weight) |
|---|---|---|---|---|---|
| 1/8 cup | 0.125 | 16 g | 2 tbsp | 30 ml | 0.564 oz |
| 1/4 cup | 0.25 | 32 g | 4 tbsp | 60 ml | 1.13 oz |
| 1/3 cup | 0.33 | 42.7 g | 5.33 tbsp | 80 ml | 1.51 oz |
| 1/2 cup | 0.5 | 64 g | 8 tbsp | 120 ml | 2.26 oz |
| 2/3 cup | 0.67 | 85.3 g | 10.7 tbsp | 160 ml | 3.01 oz |
| 3/4 cup | 0.75 | 96 g | 12 tbsp | 180 ml | 3.39 oz |
| 1 cup | 1 | 128 g | 16 tbsp | 240 ml | 4.52 oz |
| 1 1/4 cups | 1.25 | 160 g | 20 tbsp | 300 ml | 5.64 oz |
| 1 1/3 cups | 1.33 | 171 g | 21.3 tbsp | 320 ml | 6.02 oz |
| 1 1/2 cups | 1.5 | 192 g | 24 tbsp | 360 ml | 6.77 oz |
| 1 2/3 cups | 1.67 | 213 g | 26.7 tbsp | 400 ml | 7.53 oz |
| 1 3/4 cups | 1.75 | 224 g | 28 tbsp | 420 ml | 7.9 oz |
| 2 cups | 2 | 256 g | 32 tbsp | 480 ml | 9.03 oz |
| 2 1/4 cups | 2.25 | 288 g | 36 tbsp | 540 ml | 10.2 oz |
| 2 1/2 cups | 2.5 | 320 g | 40 tbsp | 600 ml | 11.3 oz |
| 3 cups | 3 | 384 g | 48 tbsp | 720 ml | 13.5 oz |
| 3 2/3 cups | 3.67 | 469 g | 58.7 tbsp | 880 ml | 16.6 oz |
Ounces here are ounces of weight (1 oz = 28.35 g), not fluid ounces. One US cup is 8 fluid ounces of volume whatever is in it, but what it weighs in ounces depends on the ingredient: a cup of cornstarch weighs about 4.52 oz. Why these two are not the same. Decimals for thirds are rounded (1/3 cup is 0.333 cups), and each linked amount opens a page comparing every ingredient at that measure.
Cite this: CupsToGrams, "Cornstarch: Cups to Grams", https://cupsngrams.com/cornstarch, figures verified . The data is free to reuse under CC BY 4.0 with a link back to this page.
About measuring cornstarch
Cornstarch, known as cornflour in Britain, is a fine white thickening powder, and one US cup weighs about 128 grams. You rarely use a full cup: it usually appears in tablespoons to thicken sauces, pie fillings and custards. Because a little goes a long way, small measuring errors have an outsized effect on how thick your sauce sets, which is why weighing even small amounts can be worth it when precision matters.
Cornstarch is used in small amounts, so even tablespoon errors change how a sauce sets.
How many grams is a cup of cornstarch?
One US cup (240 ml) of cornstarch weighs about 128 grams. Because a cup measures volume rather than weight, that figure is specific to cornstarch and does not transfer to any other ingredient: the same cup holds 125 grams of all-purpose flour and 340 grams of honey.
- 1/4 cup of cornstarch is about 32 grams
- 1/3 cup of cornstarch is about 43 grams
- 1/2 cup of cornstarch is about 64 grams
- 2/3 cup of cornstarch is about 85 grams
- 3/4 cup of cornstarch is about 96 grams
- 1 1/2 cups of cornstarch is about 192 grams
- 2 cups of cornstarch is about 256 grams
- 3 cups of cornstarch is about 384 grams
Working the other way round, 100 grams of cornstarch is about 0.781 cups, and 500 grams is about 3.91 cups.
Does it matter which cup my recipe means?
It does, though less than the ingredient itself. This page uses the US legal cup of 240 ml. An Australian metric cup is 250 ml, so a metric cup of cornstarch comes to about 133 grams, and the old British imperial cup of 284.1 ml holds about 152 grams. See cup sizes by country for every standard side by side.
Frequently asked questions
How many grams is 1 cup of cornstarch?
One US cup of cornstarch is about 128 grams. It is a fine, dense powder, heavier per cup than flour or cocoa.
How many grams is a tablespoon of cornstarch?
About 8 grams. Since a cup is around 128 grams and holds 16 tablespoons, each tablespoon is roughly 8 grams.
Is cornstarch the same as cornflour?
In Britain, yes. British cornflour is the same fine thickening starch that North America calls cornstarch, and it weighs the same per cup.
What is half of 3/4 cup of cornstarch?
Half of 3/4 cup is 3/8 cup, which is 6 tablespoons. That much cornstarch weighs 48 grams.
How many grams is 3/4 cup of cornstarch?
3/4 cup of cornstarch weighs 96 grams. That is 12 tablespoons of 8 grams each.
Where this figure comes from
We have not yet found a published reference that states a weight for a cup of cornstarch. The 128 grams on this page follows the calibration the rest of the site is built on, with butter at 227 grams per cup, water at 240, all-purpose flour at 125 and granulated sugar at 200. Treat it as a good working figure rather than a cited one. If you have a better source, tell us and we will check it and credit you.
Published figures for the same ingredient vary between references anyway, because how an ingredient is packed changes what a cup of it weighs. Treat any cup figure as accurate to within a few percent, and weigh on a scale when a recipe is sensitive. Our full approach is on the methodology page.
Figures last verified . Compiled by the CupsToGrams editorial team at FusionStudios. Spotted a value that looks off? Tell us.