Substitute for all-purpose-flour in thickening
Quick answer
Cornstarch is the most reliable swap: use 1 tablespoon cornstarch for every 2 tablespoons all-purpose flour called for. For gravies and pan sauces, arrowroot is a close second and produces a clearer result. Both must be slurried in cold liquid before adding to a hot pot.
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| Rank | Substitute | Ratio (replaces 1 cup all-purpose-flour) | Notes |
|---|---|---|---|
| #1 | Cornstarch | 1 tbsp cornstarch per 2 tbsp all-purpose flour | Cornstarch thickens at roughly twice the power of flour and produces a glossier, slightly more translucent sauce. It must be mixed into cold water first (about 1 tbsp cold water per 1 tbsp cornstarch) before whisking into hot liquid. Does not work well in dishes that will be frozen — the sauce turns watery and grainy on thawing. Also breaks down if simmered longer than a few minutes after thickening, so add it near the end of cooking. |
| #2 | Arrowroot powder | 1 tbsp arrowroot per 2 tbsp all-purpose flour | Produces a clearer, shinier finish than cornstarch — useful in fruit sauces or light pan sauces where cloudiness is unwanted. Same slurry method applies. Breaks down even faster than cornstarch when overcooked or held at a boil, so stir in right before serving. Poorly suited for dairy-heavy sauces (can turn slimy) and does not freeze well. |
| #3 | Potato starch | 1 tbsp potato starch per 2 tbsp all-purpose flour | Thickens quickly and produces a relatively neutral flavor with a slightly starchy texture if overcooked. Works well in gravies and braising liquids. Like cornstarch and arrowroot, it must be slurried in cold liquid first. Holds up somewhat better than arrowroot under brief simmering, but still degrades with extended heat. Freezes poorly. |
| #4 | Rice flour | 2 tbsp rice flour per 2 tbsp all-purpose flour (1:1 ratio) | One of the few starch-based thickeners that tolerates longer cooking and freezes reasonably well without breaking. Produces a slightly opaque, matte sauce similar to flour. Works well in longer-simmered gravies and soups. Can be whisked directly into a fat to form a roux, or slurried. Does not produce the silky sheen of cornstarch. Fine-milled rice flour (not coarse Asian-style sticky rice flour) gives the cleanest results. |
Why thickening is different
When flour thickens a sauce, it works primarily through starch gelatinization — starch granules absorb liquid and swell when heated, increasing viscosity. Pure starches like cornstarch contain no protein and far more dense starch, which is why they thicken at roughly half the volume of all-purpose flour (which is diluted by protein, fat, and moisture-absorbing gluten). The thickening method also matters: flour is typically cooked in fat first as a roux to eliminate raw starch flavor, while pure starches are almost always slurried in cold liquid, skipping the roux step entirely.
Common mistakes
The most common error is adding a starch-based substitute directly to hot liquid without making a slurry first — it clumps immediately and the lumps are very difficult to break up. A second frequent mistake is substituting cornstarch or arrowroot at a 1:1 ratio with flour, which over-thickens the dish and produces a gluey, gel-like texture. A third is continuing to boil the sauce aggressively after the starch has set — most pure starches break down under sustained heat, thinning the sauce back out and requiring more thickener to compensate.
All-purpose flour’s role in thickening is primarily about starch, not gluten — so the substitutes that work best are those that deliver concentrated starch in a predictable, consistent way. Cornstarch covers the vast majority of everyday sauce and gravy needs and is the option most food professionals would reach for first. The key discipline is always the slurry: cold liquid, fully dissolved, added to the hot pan — not the other way around.
For longer-cooked dishes, or anything headed to the freezer, rice flour is worth keeping on hand specifically for this purpose. It behaves more like all-purpose flour in terms of cooking tolerance, and it’s the only starch-based substitute here that survives both extended heat and freezing without breaking down.
Frequently asked questions
- Can I make a roux with cornstarch the same way I would with flour?
- No. Cornstarch does not behave like flour in a roux. It does not cook evenly in fat at typical roux temperatures, and the result is gritty rather than smooth. For a roux-based sauce, rice flour is the most reliable flour substitute — it can be cooked in butter just like all-purpose flour.
- Which thickener works best for a sauce that will be frozen?
- Rice flour is the best option for freezer-stable sauces. Cornstarch, arrowroot, and potato starch all undergo retrogradation when frozen and thawed, causing the sauce to weep liquid and turn grainy. Flour and rice flour hold their texture significantly better through a freeze-thaw cycle.
- My sauce thickened but then thinned out again — what happened?
- This is almost always caused by over-simmering after the starch was added, or by stirring too vigorously once the starch had set. Cornstarch and arrowroot in particular lose viscosity quickly when held at a boil. Add the slurry at the very end of cooking, bring just to a gentle simmer to activate, and pull the pan off the heat.
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