20g Cornstarch to Cups
20 grams of cornstarch is a small amount, best measured with a spoon rather than a full cup. At 128g per cup, it works out to 2.5 tablespoons.
- Cups (US Customary)
- 0.16 (⅛)
- Tablespoons
- 2.5
- Teaspoons
- 7.5
- Milliliters
- 37 ml
20 grams of cornstarch = 0.16 cups (⅛ cup / 2.5 tbsp / 7.5 tsp)
Cornstarch has a density of approximately 128g per cup. Sifted cornstarch is closer to 115g. Source: USDA FoodData Central. This is the figure used everywhere on this page, including the tablespoon and teaspoon values, so the numbers stay consistent whether you're reading the summary line, the table, or the FAQ answers below.
| Grams | Cups | Fraction | Tablespoons | Teaspoons |
|---|---|---|---|---|
| 10g | 0.08 | ⅛ | 1.3 | 3.8 |
| 15g | 0.12 | ⅛ | 1.9 | 5.6 |
| 20g | 0.16 | ⅛ | 2.5 | 7.5 |
| 25g | 0.20 | ¼ | 3.1 | 9.4 |
| 30g | 0.23 | ¼ | 3.8 | 11.3 |
The Math for 20g of Cornstarch
20g divided by 128g (the weight of one cup of cornstarch) equals 0.16 cups. Multiplying that by 16 gives 2.5 tablespoons, and by 48 gives 7.5 teaspoons, since one cup always equals 16 tablespoons or 48 teaspoons regardless of the ingredient.
Cornstarch is lighter than water, which weighs about 236g per cup. That's why 20g of cornstarch takes up more volume (37ml) than the same weight of water would (20ml). For a side-by-side look at how other ingredients compare, see the 20 grams to cups page.
Metric and Imperial Cup Sizes
The 0.16 cup figure above uses the US Customary cup (236.588ml). Recipes written outside the US sometimes use a metric cup (250ml) or an imperial (uk) cup (284.131ml) instead. At 20g, that's ⅛ metric cups or ⅛ imperial cups of cornstarch, close to the US figure but not identical. The cup standard switch in the converter above recalculates this instantly for any gram amount.
Making More or Less Than 20g
Doubling a recipe that calls for 20g of cornstarch means weighing 40g, or measuring 0.31 cups if you're working by volume instead of weight. Halving it means 10g, or 0.08 cups. Weight scales exactly with simple multiplication; cup measurements compound any scooping error each time they're doubled or halved, so weighing is more reliable the more a recipe is scaled.
How Cornstarch Compares to Similar Ingredients
Within dry goods, density still varies by ingredient. At 20g, protein powder (120g per cup) measures ⅛ cup, while rolled oats (90g per cup) measures ¼ cup, compared to ⅛ cup for cornstarch. Swapping ingredients in a recipe by cup measurement alone, without adjusting for this difference, changes the actual weight used.
Typical Uses for Cornstarch
- Fruit pie fillings typically use 20g to 30g of cornstarch as a thickener.
- Stir-fry sauces often call for 10g mixed with water as a slurry.
- Custards and puddings usually need 15g to 25g per batch.
Getting an Accurate Spoon Measurement
Dry Goods
Spoon into the cup and level off. Ingredients like cocoa powder benefit from a quick sift first to break up clumps.
For exact results
Baking soda and baking powder should always be measured with a dry measuring spoon, leveled flat — a heaping spoonful of either can meaningfully change how a baked good rises.
For every gram amount at once, the cornstarch conversion chart lists cornstarch across the full range from 1g to 1000g in one table.
Frequently Asked Questions
What is 20 grams of cornstarch in cups?+
20 grams of cornstarch is 0.16 cups, or 2.5 tablespoons.
Should I use a spoon or a cup for 20g of cornstarch?+
At 20g, a tablespoon or teaspoon measurement is usually more practical than a fractional cup. Use 2.5 tablespoons or 7.5 teaspoons.
Is 20 grams of cornstarch the same as 20 milliliters?+
Only if it weighed the same as water. 20g of water is about 20ml, while 20g of cornstarch is 37ml, because the two have different densities.
Does the answer change for a metric or imperial cup?+
Slightly. 20g of cornstarch is ⅛ metric cups or ⅛ imperial cups, close to the US figure but not identical, since each standard defines the cup at a different volume.