Cornstarch Substitute: Best Swaps for Thickening Sauces

A cornstarch substitute is another starch or flour used to thicken sauces, soups, pie fillings, and stir-fries when cornstarch is unavailable or unsuitable for a recipe. All-purpose flour is a dependable pantry option; this simple flour slurry thickens two cups of broth-based sauce, while the guide below explains how other substitutes behave and how much to use.

Ingredients

2 cups (480 ml) broth or thin sauce, preferably at room temperature or warm
2 tablespoons (16 g) all-purpose flour
3 tablespoons (45 ml) cold water
Salt and black pepper, to taste (optional)

This recipe demonstrates the flour method for thickening about two cups of liquid. The broth is included so you can follow the method as written; if you are thickening a sauce you have already made, use that sauce instead. The flour-and-water slurry is the substitute, not a one-for-one replacement by volume: start with about twice as much flour as the cornstarch amount in your original recipe.

Instructions

Make a smooth slurry. Add the flour and cold water to a small bowl. Whisk for about 30 seconds, scraping the bottom and sides, until no dry pockets or lumps remain. Cold water helps the flour disperse before it reaches the hot liquid.
Warm the liquid. Pour the broth or sauce into a small saucepan and set it over medium heat. Bring it to a gentle simmer, stirring occasionally. Do not let it boil hard, especially if the liquid contains dairy.
Whisk in the slurry. Give the slurry another quick stir, since flour can settle, then pour it gradually into the simmering liquid while whisking continuously. Adding it all at once can leave floury clumps that are difficult to smooth out.
Cook until thickened. Keep the sauce at a gentle simmer and stir for about 3 to 5 minutes, until it coats the back of a spoon and the raw-flour smell has cooked away. Flour needs a little longer cooking than cornstarch, and the finished sauce will usually be more opaque and less glossy.
Adjust and serve. If the sauce is still thinner than you want, mix 1 teaspoon (about 2.5 g) flour with 1 tablespoon (15 ml) cold water, whisk it in, and simmer for another 2 minutes before judging the texture. Season with salt and pepper if desired, then serve hot.

Tips

Use a ratio suited to the substitute. For a recipe calling for 1 tablespoon (8 g) cornstarch, begin with 2 tablespoons (16 g) all-purpose flour. For potato starch or arrowroot, use roughly 1 tablespoon (8 g) in place of 1 tablespoon (8 g) cornstarch. These are starting points; the liquid, cooking time, and desired texture affect the result.
Always disperse powder in cool liquid first. Mixing dry starch straight into a hot pan encourages lumps. Whisk the thickener with cold water, broth, or another cool liquid until smooth, then stream it into the hot dish while stirring.
Add only what you need. Thickening continues as a sauce simmers and may increase slightly as it cools. Add a small amount, allow it to cook, and reassess before adding more. A sauce that seems perfect in the pan can become too stiff after standing.
Check the package and recipe. “Flour,” “tapioca flour,” and “tapioca starch” can refer to different products in some markets, though tapioca flour and tapioca starch are commonly the same ingredient. Avoid assuming that a gluten-free baking blend will work like a pure starch; blends often contain gums or several flours and do not have a predictable thickening ratio.

Serving Suggestions

Use the flour-thickened broth as a starting point for gravy, a pan sauce, or a simple filling for pot pie. It is especially useful when a recipe can simmer for a few minutes after the thickener goes in. For a smoother finish, whisk steadily as you pour in the slurry and strain the sauce if any small lumps remain.

For a stir-fry, prepare a thinner sauce in a separate bowl and add it near the end of cooking, tossing until it coats the vegetables or other ingredients. A flour slurry is not always the best choice for a quick, glossy stir-fry sauce because it needs to cook long enough to lose its raw taste. Arrowroot or tapioca starch may suit that use better.

Serve thickened sauces promptly over rice, noodles, mashed potatoes, biscuits, or roasted vegetables. Keep the sauce at a gentle simmer only as long as needed; vigorous boiling can make some starch-thickened sauces thin out or turn pasty.

Variations

Arrowroot for a clear finish: Replace 1 tablespoon (8 g) cornstarch with about 1 tablespoon (8 g) arrowroot powder. Whisk it into cool water, then stir it into the hot liquid near the end of cooking. It can make a clear, glossy sauce, but prolonged boiling may weaken its thickening power. Dairy-based sauces can also become slick or stringy, so flour or potato starch is often a more suitable choice for those.

Potato starch for a quick thickener: Use about the same amount of potato starch as cornstarch and mix it with cold water before adding it. Stir it in toward the end and avoid a long, hard boil, which can make the texture gluey. Potato starch is a useful option when you want a fairly neutral flavor, but it may not hold its texture as well through extended cooking.

Tapioca starch for a glossy sauce: Start with about 2 tablespoons (16 g) tapioca starch for each 1 tablespoon (8 g) cornstarch, then adjust cautiously because products and recipes vary. Make a cold slurry and add it near the end of cooking. Tapioca can create a shiny, slightly stretchy texture, which works well in some fruit fillings and glossy sauces but may not be the texture you want in gravy.

Rice flour for a gluten-free alternative: Use about 2 tablespoons (20 g) rice flour for each 1 tablespoon (8 g) cornstarch, adding it gradually to cool liquid before cooking. Rice flour can have a slightly grainier finish than pure starch, so simmer it long enough to soften the texture and use a fine-mesh sieve if needed. Check the package label if avoiding gluten, since processing and cross-contact information varies by product.

Instant potato flakes for soup: For a rustic soup or stew, stir in 1 tablespoon (about 5 g) instant potato flakes at a time and wait briefly for them to absorb liquid before adding more. They thicken by absorbing moisture rather than forming the clear coating a starch slurry gives. The flakes can make the dish taste more potato-like, so they are better suited to hearty soups than delicate sauces.

Storage and Reheating

This flour slurry is best mixed just before use. If you have a prepared slurry left over, cover it and refrigerate it for up to 1 day, then whisk it thoroughly before using because the flour settles. Discard it if it has been left at room temperature for more than 2 hours; do not leave a flour-and-water mixture sitting out for extended periods.

Refrigerate finished sauce within 2 hours in a covered container. Most cooked sauces keep for 3 to 4 days in the refrigerator. Flour-thickened sauces may become thicker or develop a skin as they chill; stir in a little broth or water while reheating to loosen them. Reheat leftovers until they reach 165°F (74°C), stirring so the sauce heats evenly. Freezing is possible, but thawed sauces can separate or turn grainy; whisk while reheating, and expect that the original texture may not return completely.

Frequently Asked Questions

What is the best all-purpose substitute for cornstarch?
All-purpose flour is the most accessible general-purpose substitute. Use about 2 tablespoons (16 g) flour for every 1 tablespoon (8 g) cornstarch, and simmer the dish for several minutes to cook away the flour taste. It makes sauces more opaque and less shiny than cornstarch.

Can I substitute flour for cornstarch in a sauce at the same ratio?
Usually not. Flour has less thickening power by volume, so start with twice as much flour as cornstarch. For example, if the recipe calls for 1 tablespoon cornstarch, whisk 2 tablespoons flour with cold water, then add it gradually and simmer. If the sauce is still thin, add more slurry a little at a time.

What can I use instead of cornstarch in a pie filling?
Tapioca starch, arrowroot, or flour can work, but the finished filling will differ. Tapioca often gives fruit filling a glossy, slightly elastic texture; flour makes it cloudier; and arrowroot can be clear but may not hold up to prolonged baking or boiling. Follow a tested filling recipe when possible, since fruit juiciness and acidity change how much thickener is needed.

Can I use baking powder or baking soda to thicken a sauce?
No. Baking powder and baking soda are leavening agents, not substitutes for cornstarch. They can add an unwanted flavor and alter the dish without providing the smooth thickening you need. Choose flour, arrowroot, potato starch, tapioca starch, or another thickener suited to the recipe instead.

Will a cornstarch substitute work in cold preparations?
Not every substitute thickens without heat. Flour needs to cook, while many starches must be heated to thicken properly. If you are making a no-cook filling or dressing, use an ingredient designed for that method, or follow a recipe that specifies the thickener and process rather than stirring raw flour into the finished dish.

How do I fix a sauce that has become too thick?
Whisk in warm broth, water, or milk a tablespoon (15 ml) at a time until it reaches the texture you want. Add the liquid gradually and let the sauce simmer briefly after each addition. If it is lumpy, whisk vigorously or pass it through a fine-mesh sieve before serving.

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