The best cornstarch substitutes depend on what you're making
Cornstarch thickens sauces, gravies, and pie fillings by absorbing liquid and turning it into a gel when heated. If you don't have cornstarch on hand, arrowroot powder, potato starch, tapioca starch, and all-purpose flour all do the same job—but each one behaves slightly differently, and some work better for certain dishes than others.
The substitute you choose matters because cornstarch thickens at a lower temperature than flour does, and arrowroot breaks down if you stir it too much. Picking the wrong one can leave you with a sauce that's too thin, too lumpy, or breaks apart when you reheat it. This guide walks you through which substitute works best for what you're cooking, how much to use, and what to watch for while you cook.
Key Takeaways
- Arrowroot powder and tapioca starch create the clearest, glossiest sauces and work well for fruit pies, but they break down if overcooked or stirred too much.
- Potato starch thickens quickly and works for gravies and savory sauces, but it can become slimy if you use too much or cook it too long.
- All-purpose flour thickens reliably but produces an opaque sauce and requires cooking for at least one minute to remove the raw flour taste.
- Use one tablespoon of arrowroot, tapioca, or potato starch for every one tablespoon of cornstarch, but use two tablespoons of flour instead.
- Cornstarch substitutes behave differently when frozen, reheated, or stirred, so test your sauce before serving it to guests.
Arrowroot powder for clear, glossy sauces
Arrowroot powder is the closest match to cornstarch in how it thickens and what the finished sauce looks like. It creates a clear, glossy coating that makes fruit pies and dessert sauces look appealing, and it thickens at roughly the same temperature as cornstarch does. Use it in a one-to-one ratio: one tablespoon of arrowroot powder for every one tablespoon of cornstarch the recipe calls for.
The catch is that arrowroot breaks down if you overstir it or cook it too long. Once your sauce reaches the right thickness, stop stirring and remove it from heat. If you're making a pie filling, let it cool completely before pouring it into the crust—if it's still hot, the arrowroot will continue to break down and the filling will become runny. Arrowroot also doesn't freeze well; sauces made with it can separate or become grainy when thawed.
Tapioca starch for fruit fillings and desserts
Tapioca starch (also called tapioca flour) thickens smoothly and produces a clear, glossy result similar to arrowroot. It's especially good for fruit pie fillings because it holds up better than arrowroot when the pie is baked. Use a one-to-one ratio: one tablespoon of tapioca starch for every tablespoon of cornstarch.
Tapioca starch takes slightly longer to thicken than cornstarch—usually one to two minutes of simmering instead of 30 seconds—so don't assume your sauce is too thin and add more. Let it bubble gently for a full minute before deciding you need extra thickener. Like arrowroot, tapioca breaks down if you stir it constantly, so mix it in and then leave it alone. Tapioca can also create a slightly grainy texture if you use too much, so start with the amount the recipe calls for and add more only if the sauce is still too thin after cooking.
Potato starch for quick-thickening gravies
Potato starch thickens faster than cornstarch and works well for gravies and savory sauces. It creates a slightly opaque result, but not as cloudy as flour. Use a one-to-one ratio: one tablespoon of potato starch for every tablespoon of cornstarch. Because it thickens so quickly, add it slowly while whisking constantly to avoid lumps.
Potato starch can become slimy if you use too much or cook it too long, so measure carefully and stop cooking as soon as the sauce reaches the thickness you want. It also doesn't hold up well when reheated—the sauce may break down and become thin again. If you're making gravy ahead of time, potato starch is not the best choice. It works best for sauces you'll serve when ready.
All-purpose flour for sauces you'll cook longer
All-purpose flour is the most forgiving substitute because it doesn't break down with stirring or reheating. It works for gravies, pan sauces, and any dish where you're comfortable with a slightly opaque, matte finish instead of a glossy one. Use two tablespoons of flour for every one tablespoon of cornstarch, because flour is roughly half as powerful a thickener.
The important step with flour is cooking it long enough to remove the raw flour taste. After you add the flour and whisk it in, let the sauce simmer for at least one minute, stirring often. If you skip this step, your sauce will taste starchy and slightly bitter. Flour also creates a thicker, heavier sauce than cornstarch does, so your gravy or sauce will coat the spoon more heavily. This works well for traditional gravies but can make delicate sauces feel heavy.
How to mix and cook each substitute
The way you add the thickener to your liquid matters. For arrowroot, tapioca, and potato starch, mix the powder with a small amount of cold water or broth first—about two tablespoons of liquid per tablespoon of starch—to make a smooth slurry. This prevents lumps. Whisk the slurry into your hot sauce or gravy while stirring constantly, then let it cook until it thickens.
For flour, you have two options. You can make a slurry the same way, or you can cook the flour in a little butter or fat first for one minute (this is called a roux) and then whisk in your hot liquid. The roux method gives you more control and helps prevent lumps. Whichever method you use, keep the heat at a gentle simmer, not a rolling boil, so you can see when the sauce reaches the thickness you want.
Timing varies by substitute. Cornstarch thickens in about 30 seconds of simmering. Arrowroot and tapioca take one to two minutes. Potato starch thickens almost when ready, so watch carefully. Flour needs at least one minute of simmering to cook out the raw taste. Add your thickener slowly and give it time to work before adding more.
Common mistakes and how to avoid them
The most common mistake is using too much thickener. Start with the amount the recipe calls for, cook it, and then decide if you need more. It's easier to add more thickener than to thin out a sauce that's too thick. Remember that sauces continue to thicken slightly as they cool, so a sauce that looks a little thin while it's hot may be perfect once it cools.
Another mistake is not mixing the thickener with cold liquid first. If you dump dry starch directly into hot liquid, it will clump and you'll end up with lumpy sauce. Always make a slurry with cold liquid first, then whisk it into the hot sauce. If you do end up with lumps, strain the sauce through a fine-mesh sieve to remove them.
Don't overstir arrowroot or tapioca once they've thickened—this breaks down the starch and makes the sauce thin and runny again. Stir just enough to combine, then stop. And don't assume a sauce is done thickening after 10 seconds; give it the full cooking time before you decide it needs more thickener.
Frequently Asked Questions
Can I use baking powder or baking soda instead of cornstarch?
No. Baking powder and baking soda are leavening agents that make baked goods rise; they don't thicken sauces or liquids. They'll also change the flavor and texture of your dish. Stick with arrowroot, tapioca, potato starch, or flour.
What if my sauce breaks or becomes thin after I reheat it?
Arrowroot, tapioca, and potato starch all break down when reheated. If you need to reheat a sauce, use flour instead, or make the sauce fresh. If you've already made it with another thickener and it's broken, you can whisk in a small amount of cornstarch slurry or flour slurry to re-thicken it.
Does it matter if I use when ready tapioca instead of tapioca starch?
Yes. when ready tapioca is made from tapioca pearls that have been partially cooked and dried. It thickens differently and more slowly than tapioca starch, and it can create a grainy, beaded texture in your sauce. Use tapioca starch (the fine powder) instead.
Can I use rice flour or coconut flour?
Rice flour can work as a thickener in a pinch, but it's grainier than all-purpose flour and produces a slightly sandy texture. Coconut flour absorbs much more liquid than other flours and will make your sauce too thick and coconut-flavored. Stick with the substitutes listed above.
How much thickener do I need if the recipe doesn't say?
Start with one tablespoon of arrowroot, tapioca, or potato starch per cup of liquid you want to thicken. For flour, use two tablespoons per cup. Mix it with cold liquid first, whisk it into your hot sauce, and cook for the time listed above. If the sauce isn't thick enough, add another half-tablespoon and cook again.