Cake Flour Substitute Calculator

The formula: 14 tablespoons of flour plus 2 tablespoons of cornstarch

Making cake flour at home takes two ingredients and one minute. For every cup of cake flour a recipe calls for, do this:

• Measure 1 cup of all-purpose flour, then take out 2 tablespoons and set them aside
• Add 2 tablespoons of cornstarch to the flour
• Whisk to combine, then sift once

That leaves 14 tablespoons of flour and 2 tablespoons of cornstarch, which is about 105 grams of flour and 14 grams of cornstarch. The volume is the same as 1 cup, so you can swap it in one for one. The calculator above scales this to any amount, in cups, tablespoons and grams.

The one-step version, 1 cup of flour minus 2 tablespoons, works too, but it leaves the protein level higher. The cornstarch is what brings the protein down to cake flour territory, so the three-step version gives the better crumb.

Why cornstarch stands in for cake flour

Flour is graded by how much protein it contains, because protein turns into gluten when it meets water and gets stirred. More gluten means a chewier, sturdier baked good, which is exactly what you want in bread and exactly what you do not want in a tender cake.

Cake flour is milled from soft wheat and sits at about 7% to 9% protein. All-purpose flour runs about 10% to 12%. That gap is small on paper but shows up in the crumb. Cornstarch has almost no protein, so mixing 2 tablespoons of it into a cup of all-purpose flour dilutes the protein and pushes the blend closer to cake flour.

Cornstarch also does a second job. It coats some of the flour particles and gets in the way of gluten strands forming, which adds tenderness on top of the dilution. That is why bakers reach for it instead of just using less flour. The USDA FoodData Central database lists the protein content of wheat flours if you want to compare brands, and the FDA guidance on handling flour safely is worth a read, since flour is a raw ingredient and should not be tasted before it is baked.

Worked example: a cake that needs 3 cups of cake flour

Say a white cake recipe calls for 3 cups of cake flour. Here is the full breakdown of the substitute.

• All-purpose flour: 3 cups minus 6 tablespoons, which is 2 1/4 cups plus 2 tablespoons, or 42 tablespoons, or about 315 grams
• Cornstarch: 3 times 2 tablespoons, which is 6 tablespoons, or about 42 grams

The easy way to measure it: scoop 3 level cups of all-purpose flour, then remove 6 tablespoons. Add 6 tablespoons of cornstarch, whisk, and sift. You now have about 3 cups of substitute, ready to use in place of the cake flour.

Now compare the protein. Three cups of all-purpose flour carries roughly 33 grams of protein at 11% per cup of 105 grams. Three cups of cake flour at 8% carries about 27 grams. The cornstarch adds almost none, so the substitute lands near the cake flour number rather than the all-purpose one. That difference is what keeps the cake tender instead of bready.

Cake flour substitute amounts

This table gives the substitute for the amounts recipes call for most often. The flour column is the all-purpose flour to measure before you take any out, and the cornstarch column is what you add back.

Read it as a ratio and any amount works: 14 parts flour to 2 parts cornstarch, measured in tablespoons. For 5 cups of cake flour, use 70 tablespoons of flour and 10 tablespoons of cornstarch.

Cake flour, all-purpose and bread flour compared

Knowing where each flour sits makes the substitution easier to judge. Protein drives the texture, and the three main flours spread across a clear range.

Two substitutions go one way but not the other. You can usually use all-purpose flour where a recipe calls for cake flour and accept a slightly denser cake. You should not put cake flour into a bread recipe, because the low protein cannot build the gluten a loaf needs, and the dough will not rise the same way.

When a recipe calls for all-purpose and you only have cake flour, use 1 cup plus 2 tablespoons of cake flour for each cup of all-purpose. That adds back the flour volume the lower protein calls for.

Measuring, sifting and when to just buy cake flour

A few small habits decide whether the substitute works. Measure flour by spooning it into the cup and leveling it off, not by scooping with the cup, since scooping packs in up to 20% more flour and makes the cake dry. Level every measure with the back of a knife. Sift the flour and cornstarch together at least once, because cornstarch clumps and an unsifted batch leaves dense streaks in the cake.

Make the substitute in a batch if you bake often. Mix a few cups at a time and keep it in a labeled airtight jar for up to 3 months. Just remember it is not plain flour, so do not grab it for a bread recipe by mistake.

For most everyday cakes, the substitute is close enough that no one will notice. For a recipe where the crumb is the whole point, such as a delicate sponge or a wedding cake layer, real cake flour still wins. Buy a box when you want the best result, and keep the cornstarch trick for the times you are out and the cake is already on the counter.