1/2 Cup Cornstarch in Grams

1/2 cup of cornstarch weighs 56 g (spooned and levelled, King Arthur Baking). A full cup weighs 112 g, so the half cup is exactly half of that. Fine white starch from corn; a powerful thickener with no flavour of its own. All the figures on this page are approximate conversions based on the King Arthur Baking value, so when a recipe really matters, verify with a kitchen scale.

Why weighing cornstarch beats measuring it in cups

Half a cup of cornstarch weighs 56 g, and that measure is larger than most recipes ever use at once. Cornstarch is a powerful thickener with no flavour of its own, and a sauce that needs thickening usually takes one or two tablespoons, about 14 g, rather than a half cup. Half a cup is the amount in a large batch of custard, a big pot of gravy, or a cake where cornstarch replaces part of the flour to lighten the crumb. The power of cornstarch is why the weight matters: a tablespoon too much turns a sauce from glossy to gloopy, and a half cup measured carelessly can be 10 g heavy, which is enough to change a large batch.

Cornstarch must be mixed with cold liquid before it is added to a hot sauce, because it clumps instantly in hot liquid and the lumps never dissolve. The slurry method is the reliable one: whisk the cornstarch into a little cold water or milk until smooth, then stir it into the simmering sauce and cook for a minute until it thickens. Cornstarch also gives cakes a lighter crumb when it replaces part of the flour: a cake made with half flour and half cornstarch is tenderer than one made with flour alone, though it has less structure, so the swap works best in delicate cakes rather than in breads.

Cornstarch cups to grams conversion table

Cups Grams Tablespoons
1/8 cup 14 g 2
1/4 cup 28 g 4
1/3 cup 37.3 g 5.3
1/2 cup 56 g 8
2/3 cup 74.7 g 10.7
3/4 cup 84 g 12
1 cup 112 g 16
1 1/2 cups 168 g 24
2 cups 224 g 32
3 cups 336 g 48

The table is built around the half cup, which is the measure this page is about, with the full-cup weight of 112 g as the anchor. Every row is the full-cup weight multiplied by the fraction, so the numbers stay consistent as you scale up or down. One tablespoon of cornstarch weighs about 7 g, which is useful when a recipe calls for a spoonful rather than a cup.

Worked examples

A large custard for eight

A custard for eight people uses about 1/2 cup of cornstarch, which is 56 g, whisked into cold milk with sugar and egg yolks, then heated gently until thick. Weigh 56 g rather than measuring by cups, because cornstarch is a fine powder that compresses easily and a scooped half cup can be 10 g heavy. Whisk the cornstarch into cold milk first so it dissolves without lumps, then heat gently, stirring constantly.

Gravy for a roast dinner

Gravy for a roast dinner uses about 1/4 cup of cornstarch, which is 28 g, mixed with cold water into a slurry and stirred into the hot pan juices. Weigh 28 g on a scale that reads to the gram, because a small error in a powerful thickener is a large error in the sauce. Cook the gravy for a minute after adding the slurry so the starch thickens fully and loses its raw taste.

A light sponge cake for a celebration

A sponge cake uses about 1/2 cup of cornstarch, which is 56 g, replacing half the flour in the recipe to lighten the crumb. Weigh 56 g so the swap is exact: the cake will be tenderer than one made with flour alone, though it has less structure, so handle the batter gently and do not over-mix.

How the weight was measured

Spooned and levelled means spooning the ingredient into the measuring cup until it is heaped, then sweeping a straight knife across the top to level it off. Never scoop the cup through the bag or jar, and never tap the cup down, because both pack the ingredient and add weight. The difference between a spooned cup and a scooped cup can be 15 to 25 percent, which is enough to change a bake from tender to tough, so the method matters as much as the number.

The source for the figure on this page is King Arthur Baking, and the confidence in the value is high. King Arthur Baking publishes a standard ingredient weight chart that recipe developers use as a reference, and this page follows that chart rather than any single cookbook. Where the chart gives a range or a note, we say so plainly instead of hiding the uncertainty. All the figures here are approximate conversions: natural ingredients vary by brand, variety, moisture and how finely they are chopped or ground, so when a recipe really matters, verify the weight with a kitchen scale.

Practical guidance

Store cornstarch in an airtight container in a cool, dry place, indefinitely, because it is a pure starch that does not go rancid. Always spoon the cornstarch into the cup and level it, never scoop, because the fine powder compresses easily. Mix cornstarch with cold liquid before adding it to a hot sauce, because it clumps instantly in hot liquid. Cook the sauce for a minute after adding the cornstarch so it thickens fully and loses its raw taste. Do not over-cook a cornstarch-thickened sauce, because prolonged heat can thin it again. If you do not have a scale, spoon the cornstarch loosely into the half cup and level it, remembering that the 56 g figure is approximate.

Common mistakes with half-cup measures

The most common mistake is treating a half cup as a casual measure. Half a cup of flour is 60 g, and a scooped half cup can easily weigh 70 g or more, which is a 15 percent error in a recipe that may only contain two or three cups of flour in total. Small measures carry the largest relative errors, so weighing matters more, not less, at this size. The second mistake is using a liquid measuring jug for dry flour: the meniscus line is designed for liquids, and flour measured in a jug is almost always over- or under-filled. Use a dry cup, or a scale. The third is assuming every flour weighs the same per half cup: the flours on this page range from about 42 g to about 82 g per half cup, so swapping flours cup for cup without adjusting the weight changes the recipe. Finally, do not pack flour into the half cup to make it look full: spoon and level, every time.

Frequently asked questions

How many grams is 1/2 cup of cornstarch?

1/2 cup of cornstarch weighs 56 g when spooned and levelled, according to King Arthur Baking, which lists 112 g per cup. The figure is approximate, because the fine powder compresses easily, so verify with a kitchen scale when it matters.

How do I use cornstarch without lumps?

Mix it with cold liquid first to make a smooth slurry, then stir the slurry into the hot sauce and cook for a minute. Cornstarch clumps instantly in hot liquid, so never add the dry powder directly to a hot sauce.

How much cornstarch thickens a sauce?

About 1 tablespoon, 7 g, thickens 250 ml of liquid to a light sauce, and 2 tablespoons thickens it to a gravy. Weigh the cornstarch rather than spooning it, because a heaped tablespoon can hold half as much again as a level one.

Can cornstarch replace flour in a cake?

Partly. Replacing up to half the flour with cornstarch lightens the crumb, because cornstarch has no gluten. Weigh the cornstarch rather than measuring by volume, and expect a tenderer cake with less structure.

How many cups is 100 g of cornstarch?

100 g of cornstarch is about 0.89 cups, or just under 1 cup. At 112 g per cup, divide 100 by 112 to get the answer, and use a scale for the most accurate result.

Related conversions

If you need a different amount, the table above scales in both directions, and the converter tool will do the maths for any quantity. When a recipe really matters, weigh the ingredient on a kitchen scale rather than trusting the cup alone, because the figures on this page are approximate and natural ingredients vary by brand, variety and moisture.