Use twice as much flour as cornstarch, and expect different results
Cornstarch and flour thicken differently. Cornstarch is pure starch with no protein, so it creates a clear, glossy sauce. Flour contains protein and absorbs liquid more slowly, so it produces a cloudier, less shiny result and needs heat to set up its thickening power. If you swap them one-to-one, your sauce will be too thin.
The practical rule: use about twice the amount of flour that the recipe calls for in cornstarch. A recipe asking for one tablespoon of cornstarch becomes two tablespoons of flour. This ratio works for gravies, sauces, and pie fillings, though the final texture will be noticeably different — thicker, less transparent, and with a slightly floury taste if you do not cook it long enough.
Flour works best in dishes that cook for several minutes after thickening, like stews, pot pies, and pan sauces. It does not work well in recipes where appearance matters and the sauce must stay clear, such as glazes for fruit tarts or Asian stir-fries.
Key Takeaways
- Replace one tablespoon of cornstarch with two tablespoons of all-purpose flour, since flour thickens less efficiently.
- Flour produces a cloudy, matte sauce instead of the glossy, transparent result cornstarch gives.
- Cook flour-thickened sauces for at least one to two minutes after they reach a boil to remove the raw flour taste.
- Flour works in gravies, stews, and pot pies but not in dishes where a clear, shiny sauce is essential.
- Make a slurry by mixing flour with cold water or broth before adding it to hot liquid, just as you would with cornstarch.
How to make a flour slurry
A slurry prevents lumps. Mix two tablespoons of flour with three to four tablespoons of cold water, broth, or milk in a small bowl and stir until smooth. The liquid should be cold, not hot, so the flour does not cook on contact and form clumps.
Pour the slurry slowly into your simmering sauce or broth while stirring constantly. Add it gradually — you can always add more if the sauce is still too thin, but you cannot remove it once it is in. Stir for one to two minutes after adding to let the flour cook and thicken fully. The sauce will continue to thicken slightly as it cools.
Flour in gravies and pan sauces
Flour is the traditional thickener for pan sauces and gravies because it is already in most kitchens and works well with meat drippings. After you remove meat from a pan, leave the drippings in the bottom. Sprinkle two tablespoons of flour over the drippings and stir constantly for one minute to cook out the raw flour taste — this step is called making a roux.
Pour in your liquid (broth, wine, or water) slowly while whisking to prevent lumps. Bring the mixture to a gentle boil and cook for two to three minutes, stirring often, until it reaches the thickness you want. The sauce will be opaque and have a slightly thickened, gravy-like consistency. Season with salt and pepper at the end.
Flour in pie fillings and desserts
Flour thickens fruit pie fillings but produces a noticeably different texture than cornstarch. The filling will be cloudier and less glossy, and you may taste flour if you do not cook it long enough. Use two tablespoons of flour per cup of fruit juice or liquid.
Mix the flour with a tablespoon of sugar and a pinch of salt, then toss it with your fruit before pouring into the crust. The sugar helps distribute the flour evenly. Bake as normal — the heat will cook the flour and thicken the filling. The result is still edible and tastes fine, but the appearance will not match a cornstarch-thickened pie.
When flour does not work well
Avoid flour in dishes where you need a clear, glossy sauce. Stir-fries, glazes for fruit tarts, and Asian sauces all depend on the transparency and shine that cornstarch provides. Flour will make these dishes look dull and muddy.
Flour also does not work in cold sauces or puddings that do not get cooked after thickening. Cornstarch sets up as it cools and creates a smooth texture. Flour needs heat to thicken and will leave a grainy, unpleasant mouthfeel in cold dishes. For puddings and custards, use egg yolks or gelatin instead.
Other flour alternatives if you want a clearer result
If you want a sauce closer to what cornstarch produces, consider arrowroot powder or tapioca starch. Both thicken like cornstarch and create a clear, glossy sauce. Use them in a one-to-one ratio with cornstarch — one tablespoon of cornstarch becomes one tablespoon of arrowroot or tapioca starch. They cost more and are less common in home kitchens, but they work in any recipe cornstarch does.
Potato starch is another option and works similarly to cornstarch, though it can break down if overcooked or stirred too much. Use it in a one-to-one ratio and avoid vigorous stirring once the sauce has thickened.
Frequently Asked Questions
Can I use self-rising flour instead of all-purpose flour?
No. Self-rising flour contains salt and baking powder, which will affect the taste and texture of your sauce or filling. Stick to all-purpose flour or cake flour. Cake flour is finer and may thicken slightly faster, but the ratio stays the same — use twice as much as you would cornstarch.
What if my flour sauce tastes floury?
You did not cook it long enough. After adding the flour slurry or roux to your liquid, let it boil gently for at least one to two minutes while stirring. This cooks out the raw flour taste. If the sauce is already in a dish, you can reheat it on the stovetop for another minute or two.
Why is my flour sauce lumpy?
The flour was added to hot liquid without being mixed with cold liquid first, or it was not stirred enough while cooking. Always make a slurry by mixing flour with cold water before adding it to hot liquid. Stir constantly as you pour it in and for at least one minute after.
Can I use flour in a slow cooker recipe that calls for cornstarch?
Yes, but add it near the end of cooking. Flour needs direct heat and stirring to thicken properly. If you add it at the start, it may not thicken at all. Stir in a flour slurry during the last 30 minutes of cooking and set the slow cooker to high heat so the sauce reaches a gentle boil.