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Cornstarch to Flour Thickener Converter

Convert cornstarch to flour or another starch for thickening sauces and gravies — flour thickens at about half the strength, so you need twice as much.

Cornstarch in recipe

Thickener you have

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How it works

Flour = cornstarch × 2 · Arrowroot / tapioca / potato starch ≈ cornstarch × 1

Cornstarch is nearly pure starch, so it thickens with roughly twice the power of all-purpose flour, which is only about 75% starch by weight. That means you need about two tablespoons of flour for every one of cornstarch. The pure root and grain starches — arrowroot, tapioca and potato — are close to cornstarch in strength (about 1:1) but differ in clarity and heat tolerance, so the swap is as much about texture as quantity.

Worked example

A gravy calls for 2 tablespoons of cornstarch but you only have flour. Multiply by 2 to get 4 tablespoons (1/4 cup) of flour, whisk it into cold liquid to avoid lumps, and simmer a few extra minutes to cook out the raw-flour taste.

Frequently asked questions

Why does flour need twice the amount of cornstarch?

Cornstarch is almost 100% starch, while all-purpose flour is only about 75% starch (the rest is protein and other components that do not thicken). So it takes roughly two parts flour to match one part cornstarch, and flour makes the sauce cloudy rather than glossy.

How do I add these without lumps?

Make a slurry: whisk cornstarch or a pure starch into a little cold liquid first, then stir it into the hot pan. Flour is best cooked into fat as a roux, or shaken with cold water, before it hits the hot liquid.

Which thickener holds up best when reheated?

Cornstarch and flour tolerate reheating reasonably well; arrowroot, tapioca and potato starch can thin out or turn stringy if boiled hard or held a long time, so add them near the end and avoid a rolling boil.

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This calculator is for educational purposes. Double-check important results before acting on them.