Cornstarch — Measurement Converter
Cornstarch (also called cornflour) weighs 120 g per US cup — so a recipe in cups and a recipe in grams can be swapped either way. 100 g is 7/8 cup, and 2 cups is 240 g.
💡 Tip: As a thickener, 1 tbsp cornstarch thickens about 1 cup of liquid. Always mix it with cold water into a slurry first, or it clumps when it hits heat.
Cornstarch cup measurements, in grams
| Cups | Grams | Ounces |
|---|---|---|
| 1/4 | 30 | 1.06 |
| 1/3 | 40 | 1.41 |
| 1/2 | 60 | 2.12 |
| 2/3 | 80 | 2.82 |
| 3/4 | 90 | 3.17 |
| 1 | 120 | 4.23 |
| 1 1/2 | 180 | 6.35 |
| 2 | 240 | 8.47 |
| 2 1/2 | 300 | 10.6 |
| 3 | 360 | 12.7 |
| 4 | 480 | 16.9 |
Cornstarch as a thickener: tablespoon ratios
As a rule of thumb, 1 tablespoon of cornstarch thickens about 1 cup of liquid into a pourable sauce; use a little more for gravy or pie filling. Always stir it into cold water first to make a slurry — dropped straight into hot liquid it seizes into lumps.
Swapping from a flour-thickened recipe? Cornstarch is roughly twice as strong, so 1 tablespoon of cornstarch replaces about 2 tablespoons of flour. It also sets up clearer and glossier, which is why it is the usual choice for fruit pies and stir-fry sauces.
Cornstarch by weight: grams to cups
| Grams | Amount | Ounces |
|---|---|---|
| 25 | 1/4 cup | 0.88 |
| 50 | 3/8 cup | 1.76 |
| 100 | 7/8 cup | 3.53 |
| 125 | 1 cup | 4.41 |
| 150 | 1 1/4 cups | 5.29 |
| 175 | 1 1/2 cups | 6.17 |
| 200 | 1 2/3 cups | 7.05 |
| 250 | 2 1/8 cups | 8.82 |
| 300 | 2 1/2 cups | 10.6 |
| 400 | 3 1/3 cups | 14.1 |
| 500 | 4 1/8 cups | 17.6 |
Spoon reference: 1 tablespoon ≈ 7.5 g, 1 teaspoon ≈ 2.5 g.
How cornstarch compares with other flours & starches
120 g per cup places cornstarch in the middle of its category — lighter than self-rising flour (125 g) and heavier than '00' flour (116 g).
It weighs the same per cup as all-purpose flour (120 g), so those two swap one-for-one whether you measure by cup or by scale.
Frequently asked questions
- How many grams is 1 cup of cornstarch?
- Reckon on 120 grams per US cup of cornstarch — about 4.23 ounces.
- How many grams in a tablespoon of cornstarch?
- About 7.5g per tablespoon, and roughly 2.5g per teaspoon.
- How many grams is 2 cups of cornstarch?
- 2 cups of cornstarch is 240g (at 120g per cup).
- Is cornstarch the same as cornflour?
- In the UK, Australia and many other countries, 'cornflour' means exactly what Americans call cornstarch — the fine white thickening powder. Note that US 'corn flour' is different: it is ground whole corn, used like a flour.
- How much cornstarch do I need to thicken a sauce?
- Use about 1 tablespoon of cornstarch per cup of liquid for a medium-thick sauce. Mix it into a little cold water first to make a slurry, then stir that into the hot liquid.
- Can I substitute cornstarch for flour as a thickener?
- Yes. Cornstarch has about twice the thickening power, so use roughly half as much: 1 tablespoon of cornstarch in place of 2 tablespoons of flour.
- How many cups is 100g of cornstarch?
- 100 grams of cornstarch is about 7/8 cup.
- How many cups is 150g of cornstarch?
- 150 g of cornstarch works out at roughly 1 1/4 cups.
- How many cups is 200g of cornstarch?
- 200 g of cornstarch works out at roughly 1 2/3 cups.