112 g of cornstarch is 1 cup. Cornstarch is light and powdery, and it is one of the most powerful thickeners in the kitchen: a single tablespoon can thicken a whole cup of liquid. It is measured spooned and levelled, and it must be mixed with cold liquid before it meets heat, or it will form lumps that no amount of stirring will remove.
All figures on this page are approximate, and they come from King Arthur Baking, measured spooned and levelled. When a recipe has to work the first time, verify with a kitchen scale.
Conversion table
| Cups | Grams of cornstarch |
|---|---|
| 1/4 cup | 28 g |
| 1/3 cup | 37.3 g |
| 1/2 cup | 56 g |
| 2/3 cup | 74.7 g |
| 3/4 cup | 84 g |
| 1 cup | 112 g |
| 1 1/2 cups | 168 g |
| 2 cups | 224 g |
| 3 cups | 336 g |
| 4 cups | 448 g |
Quick reference: 100 g of cornstarch is about 0.89 cups, and 50 g is about 0.45 cups. All figures are approximate; verify with a kitchen scale when it matters.
Method and source
The figure on this page comes from King Arthur Baking, measured spooned and levelled. Fine white starch from corn; a powerful thickener with no flavour of its own. Thickening sauces, gravies and custards; lightening cakes.
All results on this page are approximate. Ingredient weights vary with brand, humidity, temperature and how firmly you pack the cup, so when a recipe has to work the first time, weigh the ingredient on a kitchen scale and use the numbers here as a guide.
Worked examples
A fruit pie filling that holds its shape
A cherry pie filling uses 28 g of cornstarch, a quarter of a cup, tossed with the fruit and sugar before it goes into the crust. The cornstarch thickens the juices as the pie bakes, so the slices hold together instead of running all over the plate. Too little and the filling is soupy; too much and it tastes chalky.
A stir-fry sauce with a glossy finish
A stir-fry sauce uses 14 g of cornstarch, about 2 tablespoons, mixed with cold water into a slurry and stirred into the pan at the end. The sauce thickens in seconds and turns glossy. The slurry step is essential: cornstarch added dry to a hot pan clumps instantly.
Lightening a sponge cake
A sponge cake recipe replaces 28 g of the flour with cornstarch, a quarter of a cup, to make the crumb finer and more tender. Cornstarch has no gluten, so it dilutes the gluten in the flour and gives a softer cake. This is a useful trick for any cake that needs a delicate crumb.
Practical guidance
Spoon the flour into the cup and level it off with a straight edge. Scooping straight from the bag packs the flour down and can add 20 g or more per cup, which is enough to turn a tender cake dry and dense. Do not sift before measuring unless the recipe says sifted, because sifting adds air and changes the weight. If you bake often, the single best upgrade is a kitchen scale: weighing flour removes the biggest source of variation in home baking entirely. Until then, spoon and level every time, and use the same cup for the whole recipe so any small error stays consistent.
Scaling is straightforward once you know the cup weight. Doubling a recipe that calls for 112 g of cornstarch means measuring 224 g, or 2 cups, and tripling it means 336 g, or 3 cups. Halving is just as easy: half a cup is 56 g. The key is to scale every ingredient by the same factor, because changing one ingredient without changing the others throws the recipe out of balance. A cake scaled by half still needs half the flour, half the sugar, half the butter and half the cornstarch, not just half of one of them. If you are scaling a recipe by an awkward factor, like two thirds, weigh the cornstarch rather than trying to measure two thirds of a cup in a jug, because the jug markings are not precise enough for fractions of a cup.
When should you weigh cornstarch instead of measuring it? Whenever the recipe has to work the first time, and whenever the amount is large. A kitchen scale costs less than a single failed cake, and it removes the biggest source of variation in home cooking: the way ingredients pack into a cup or a spoon. Put the bowl on the scale, press tare, and add the cornstarch until the display shows the number you need. There is nothing to wash afterwards except the bowl, and the result is the same every time. For small amounts, a level spoon is accurate enough, and for liquids, a jug is fine, but for anything where precision matters, the scale is the tool to reach for.
Storage. Airtight container, cool and dry, indefinitely.
- Always mix cornstarch with cold liquid before heating.
- Use half as much cornstarch as flour for the same thickening.
- Store airtight; it keeps indefinitely.
Frequently asked questions
How much cornstarch is in a tablespoon?
One tablespoon of cornstarch weighs about 7 g, and one teaspoon is about 2.3 g. A quarter of a cup, a common amount for pie fillings, is 28 g.
Why must cornstarch be mixed with cold liquid first?
Cornstarch granules swell and burst when they meet hot liquid, and if they are dry they clump together before they can disperse. Mixing it with cold water first separates the granules, so they thicken evenly when heated. This mixture is called a slurry.
Can I substitute flour for cornstarch?
Yes, but you need twice as much: use 2 tablespoons of flour for every tablespoon of cornstarch. Flour also makes sauces opaque and cloudy, while cornstarch gives a clear, glossy finish, so the result will look different.
Does cornstarch thicken the same as flour?
No. Cornstarch is about twice as powerful as flour, and it thickens at a lower temperature. It also gives a glossy, translucent finish, while flour gives a matte, opaque one. Use cornstarch for fruit pies and Asian sauces, and flour for gravies and bechamel.
How long does cornstarch keep?
Indefinitely, in an airtight container in a cool, dry place. It is a pure starch with no fat to go rancid, so it does not expire in any practical sense, though it can absorb moisture and clump if stored in a humid kitchen.
Common mistakes to avoid
The most common mistake with flour is scooping it straight from the bag, which packs it down and can add 20 g or more per cup. The second is shaking or tapping the cup to settle the flour, which has the same effect. The third is measuring flour that has just been sifted as if it were unsifted, because sifted flour is lighter and a cup of it weighs less. The fourth mistake is using a wet cup or spoon, because damp flour clumps and sticks, and the measurement becomes unreliable. Finally, do not assume that all flours weigh the same: a cup of whole wheat flour is 113 g, a cup of almond flour is 96 g, and a cup of rice flour is 142 g, and swapping them cup for cup without adjusting will change the recipe. When in doubt, weigh the flour, because a scale removes every one of these mistakes at once.