If you have ever been ready to thicken your favorite soup or stew and found that you are missing cornstarch, your recipe could have been saved by knowing some common substitutes. This essential ingredient functions as a thickening agent in gravy, soups and stews, but it also serves as an anti-caking agent and prevents things like shredded cheese from becoming a clumpy mess. No matter what your cooking need, should you find yourself without this starch you may find you already have a substitute in your kitchen.

Wheat Flour

Wheat flour offers a starchy substitute for cornstarch, also known as corn flour. Two tbsp. of all-purpose flour will act as a substitute for 1 tbsp. of cornstarch for thickening your favorite recipes. All-purpose flour will add some color distortion to the mixture and may also bring an additional flavor to the mixture that is not present in cornstarch mixtures.

Plant Starch

Arrowroot, a perennial plant, can also be used as a cornstarch substitute. The ratio of this substitution is 2 tsp. arrowroot for 1 tbsp. of cornstarch. Arrowroot will operate as a thickening agent much like its cornstarch counterpart, but will also permit overcooking, unlike cornstarch. If you have a tendency to overcook your gravy or stew, arrowroot may be the thing you are looking for. Arrowroot is, however, typically more expensive than cornstarch.

Rice Flour

Rice flour can be added as a thickening agent or a baking ingredient in place of cornstarch in a one to one ratio -- 1 tbsp. of rice flour for 1 tbsp. of cornstarch. Rice flour is ground rice that presents a starchy white powder. Rice flour also has the additional benefit of thickening quickly. Rice flour is typically inexpensive and can be found in most grocery stores or Asian markets.

Tuber Starches

Tapioca, a starch derived from cassava or manioc, can also replace cornstarch. Four tsp. of quick-cooking tapioca can be used in place of 1 tbsp. of cornstarch in a pinch. Tapioca will also operate as a thickening agent. This substitute is best applied to dishes that require refrigeration since the starch does not clump like other starches when it congeals; for example, in tapioca pudding.