How Many Grams in a Cup of Cornstarch? (128 g)
1 US legal cup of Cornstarch = 128 grams (4.52 ounces). One tablespoon = 8 grams, and one teaspoon = 2.67 grams.
Portion baseline measured as 1 cup according to official USDA laboratory reference testing.
Cornstarch: Fractional Cup to Grams Conversion Table
| Portion / Fraction | Grams (g) | Ounces (oz) | Equivalent Tablespoons |
|---|---|---|---|
| 1/8 cup | 16 g | 0.56 oz | 2 tbsp |
| 1/4 cup | 32 g | 1.13 oz | 4 tbsp |
| 1/3 cup | 42.7 g | 1.51 oz | 5.3 tbsp |
| 1/2 cup | 64 g | 2.26 oz | 8 tbsp |
| 2/3 cup | 85.3 g | 3.01 oz | 10.7 tbsp |
| 3/4 cup | 96 g | 3.39 oz | 12 tbsp |
| 1 cup | 128 g | 4.52 oz | 16 tbsp |
| 1 1/2 cups | 192 g | 6.78 oz | 24 tbsp |
| 2 cups | 256 g | 9.04 oz | 32 tbsp |
| 3 cups | 384 g | 13.56 oz | 48 tbsp |
| 4 cups | 512 g | 18.08 oz | 64 tbsp |
Interactive Cornstarch Converter
Type any amount or choose a unit to calculate instant weights and volumes
Why the Weight of Cornstarch Varies in Baking
Cornstarch contains fine milled grain particles that settle and compact significantly during transit and storage. Ambient humidity also causes dry flour to absorb airborne moisture, increasing its weight without expanding volume. Spooning vs. direct cup scooping creates the largest real-world weight difference.
Flours & Grains Measuring Technique
Aerate with a spoon, scoop lightly, and level. Cornstarch easily compresses into dense chalky clumps if scooped forcefully.
Atmospheric Altitude Context
At 5280 ft elevation, lower atmospheric pressure accelerates moisture evaporation. Ensure Cornstarch is measured strictly by weight (128g/cup) rather than volume scoop to prevent baking inconsistencies.
International Cup Size Weights for Cornstarch
Standard cup volumes vary between countries. If following a UK, Australian, or Canadian recipe, use these computed gram equivalents for Cornstarch:
| Standard Cup Standard | Volume (mL) | Calculated Grams (g) | Ounces (oz) | Primary Geographic Region |
|---|---|---|---|---|
| US Legal Cup (USDA Standard) | 240 mL | 128 g | 4.52 oz | United States (FDA nutrition labeling) |
| US Customary Cup | 236.6 mL | 126.2 g | 4.45 oz | United States (Standard kitchen measuring sets) |
| Metric Cup | 250 mL | 133.3 g | 4.7 oz | Australia, New Zealand, Canada, South Africa, UK |
| Imperial Cup | 284.1 mL | 151.5 g | 5.34 oz | Traditional British & Commonwealth recipes (1/2 pint) |
Related Flours & Grains Conversions
Frequently Asked Questions About Cornstarch
Why does a cup of Cornstarch weigh different amounts?
Cornstarch settles and packs tightly in the bag during shipping. Scooping directly with a measuring cup compresses the particles, cramming up to 140–150 grams into the cup. In contrast, fluffing with a fork and spooning gently into the cup yields the standard benchmark of approximately 128 grams. Weighing with a digital kitchen scale eliminates this volume variation entirely.
Should I sift Cornstarch before or after measuring?
Pay close attention to the recipe phrasing: "1 cup Cornstarch, sifted" means measure 1 cup first, then sift it into your mixing bowl. "1 cup sifted Cornstarch" means sift the flour into a mound first, then gently spoon 1 cup from that aerated mound. When measuring by weight on a gram scale, sifting timing has zero effect on the total flour mass.
How many grams of Cornstarch are in one tablespoon?
One level US tablespoon of Cornstarch weighs approximately 8 grams, and one level teaspoon weighs 2.67 grams. There are 16 tablespoons in 1 standard US cup (128g).
Can I swap Cornstarch 1:1 by volume with all-purpose flour?
No. Different flours vary widely in protein content, fiber absorption, and bulk density. Substituting by volume (cups) alters batter hydration and gluten development. Always substitute alternative flours by weight in grams rather than volume, and monitor whether your dough requires additional liquid.
How does altitude affect measuring Cornstarch?
At higher elevations (3,000+ ft), dry atmospheric pressure accelerates moisture evaporation from dry pantry goods, making Cornstarch drier and prone to packing denser per scoop. Weighing strictly to 128 grams per cup prevents adding excessive dry solids to your batter.
Authoritative Laboratory Citation: USDA SR Legacy
Exact 100% agreement: USDA SR Legacy portion is 128g/cup (1 tbsp = 8g). King Arthur chart lists 128g.