To make 1 cup of cake flour substitute: start with 1 cup of all-purpose flour, remove 2 tablespoons, and replace them with 2 tablespoons of cornstarch. Sift together at least twice. This lowers the effective protein content from all-purpose flour’s 10–12% to approximately 7–9%, close to commercial cake flour’s 7–8%.
Use the cups-to-grams calculator to convert any cake flour amount to grams if you prefer to weigh.
Step-by-step instructions
- Measure 1 level cup of all-purpose flour into a bowl.
- Remove 2 tablespoons of flour from the cup (use those 2 tablespoons for something else, or discard).
- Add 2 tablespoons of cornstarch to the cup.
- Sift the flour-cornstarch mixture together at least twice. Sifting ensures the starch is fully incorporated and distributed — skipping this step can leave starchy pockets.
- Use in place of 1 cup cake flour.
Why this works
Cornstarch (pure starch, no protein) dilutes the protein in all-purpose flour. Protein develops into gluten when mixed with water; less gluten means a more tender, delicate crumb. The ratio (14 tbsp flour + 2 tbsp cornstarch) brings the protein content close enough to true cake flour that most bakers can’t distinguish the results.
| Flour type | Protein % | Gluten strength |
|---|---|---|
| Pastry flour | 8–9% | Very low |
| Cake flour (commercial) | 7–8% | Low |
| AP flour + cornstarch sub | ~9% | Low-medium |
| All-purpose flour | 10–12% | Medium |
| Bread flour | 12–14% | High |
The substitute sits slightly above commercial cake flour in protein, so it’s not identical — but it produces results indistinguishable in most home baking.
Weight measurements for the substitute
| Cake flour called for | All-purpose flour | Cornstarch |
|---|---|---|
| 1/4 cup | 3.5 tbsp AP flour | 1/2 tbsp cornstarch |
| 1/3 cup | ~4.5 tbsp AP flour | ~2 tsp cornstarch |
| 1/2 cup | 7 tbsp AP flour | 1 tbsp cornstarch |
| 1 cup | 14 tbsp AP flour | 2 tbsp cornstarch |
| 2 cups | 28 tbsp AP flour | 4 tbsp cornstarch |
In grams: for 1 cup of cake flour (about 113 g), use about 100 g all-purpose flour + 14 g cornstarch.
When the substitute works best
The substitute works well in:
- Sponge cakes and chiffon cakes
- White and yellow layer cakes
- Cupcakes
- Angel food cake
- Delicate muffins
The substitute works less well in:
- Recipes requiring very low protein (true cake flour has 7–8%; your substitute is ~9%)
- Ultra-fine-crumb bakes where a pastry flour or sifted cake flour would be specified
Can I use whole wheat flour instead?
No — whole wheat flour has higher protein and added bran, which would actually toughen the crumb in the opposite direction. For low-protein needs, stick with the AP + cornstarch sub or buy real cake flour.
Bleached vs. unbleached cake flour
Commercial cake flour is typically bleached (chlorinated), which weakens gluten further and slightly acidifies the flour. Bleached cake flour produces a finer, whiter crumb than unbleached. Your AP + cornstarch substitute is unbleached, so it will produce a slightly less white, slightly less fine crumb. For most home baking, this difference is invisible.
King Arthur Baking sells an unbleached cake flour, which compares more directly to the AP + cornstarch substitute.
Recipes where real cake flour is worth buying
For most home bakers, the substitute works perfectly. But for these specific applications, buying real cake flour makes a visible difference:
- Wedding cakes or tiered cakes where crumb texture is judged closely
- Japanese milk bread and cotton-soft cakes (the extremely soft, pull-apart texture relies on low protein)
- Swiss roll cakes that must be rolled without cracking — the lower protein reduces breakage
- Chiffon cakes with very light egg foam where any extra gluten deflates the structure
For everyday birthday cakes, cupcakes, and muffins, the substitute is indistinguishable.
How to measure the substitute correctly
When the recipe gives cup amounts, make the substitute the same way you’d measure regular flour:
- Fluff the all-purpose flour in its bag.
- Spoon flour into the cup until it overflows.
- Level off the top with a straight edge.
- Remove 2 tablespoons of the measured flour.
- Add 2 tablespoons of cornstarch directly to the same cup.
- Sift together twice.
If the recipe gives grams (for example, “113 g cake flour”), use 100 g of all-purpose flour + 14 g of cornstarch. Sift before using.
Substituting cake flour in the other direction
If a recipe calls for all-purpose flour but you only have cake flour, the swap works too — with one adjustment. Cake flour is lower in protein, so the resulting baked good will be more tender and may crumble slightly more than intended. For cookies and quick breads, this is rarely a problem. For bread or pizza dough, cake flour lacks the protein needed for structure and is not a suitable replacement.
Substituting 1 cup of cake flour for 1 cup of all-purpose flour produces a result that is slightly lighter and more fragile — fine for cakes and muffins, problematic for anything that needs chew or structure.
Pastry flour: the middle ground
Between all-purpose and cake flour sits pastry flour, with a protein content of 8–9%. It’s an underused option for recipes where all-purpose flour makes baked goods slightly tough but cake flour would be too delicate:
- Pie crust: pastry flour produces a tender, flaky crust that’s easier to roll than one made with all-purpose
- Tart shells and shortbread: the lower gluten gives a sandier, more crumbly texture
- Muffins and biscuits: slightly more tender than all-purpose without the fragility of cake flour
Pastry flour can replace all-purpose flour 1:1 in any of these applications. It’s widely available online and in some grocery stores. Whole wheat pastry flour (also called soft whole wheat) is made from the same low-protein soft wheat and adds fiber while maintaining tenderness.
Commercial cake flour brands compared
| Brand | Protein % | Bleached | Notes |
|---|---|---|---|
| Swans Down | ~6.9% | Yes | Very finely milled; classic for Southern cakes |
| Softasilk (Betty Crocker) | ~6.9% | Yes | Similar to Swans Down; widely available |
| King Arthur Unbleached Cake Flour | ~10% | No | Higher protein than standard cake flour; different performance |
| Bob’s Red Mill Super-Fine Cake Flour | ~8% | No | Good middle-ground option; more widely stocked |
Note the King Arthur Unbleached Cake Flour is closer to pastry flour in protein content and behavior — it will produce a slightly less delicate crumb than bleached cake flour. Their weight per cup is also listed differently from other brands (they list it at 120 g vs. the 113 g typical of bleached cake flour). For the most delicate results, use a bleached cake flour or the AP + cornstarch substitute.