Measure 1 cup of all purpose flour, remove 2 tablespoons, and replace them with 2 tablespoons of cornstarch, then sift the blend together at least three times so the two powders distribute evenly. That swap drops the gluten-forming protein closer to cake flour’s 7–9% range and rescues a tender crumb when cake flour is nowhere on the shelf.
You will get the exact cup and gram ratios, a weight-based shortcut, the recipes where the swap truly works, plus fixes for cakes that turned out tough, gummy, or cracked.
Cake Flour Exists Because Protein Content Matters
Flour looks like one ingredient, but the protein hiding in the kernel changes everything it touches in the oven. Cake flour lands at 7–9% protein, while all purpose flour sits at 10–12%, and that narrow gap decides whether your bake turns out tender or tough.
When flour meets liquid, two proteins called glutenin and gliadin link up and form gluten. Less protein means fewer links, which is exactly what gives cakes their soft, fine crumb. Higher protein flour builds the chewy, elastic structure that breads, bagels, and pizza dough depend on for their rise and chew.
Why Baking Recipes Calibrate to Cake Flour
A recipe written for cake flour has been balanced around its low-protein behavior, which means less liquid absorption, a shorter mixing window, and a lighter final texture. Swap in straight all purpose flour and the batter drinks more liquid, the gluten sets up faster, and the finished crumb tightens up noticeably.
King Arthur Flour and Bob’s Red Mill both publish protein percentages on the bag, which is why bakers who track results tend to reach for those brands. Gold Medal’s all purpose flour can drift higher in protein depending on the harvest year, so a recipe that worked once can fail the next time you bake it.
That same harvest drift is exactly why home bakers reach for the cornstarch shortcut in the first place.
The Cornstarch Trick That Mimics Cake Flour
Cornstarch steps in for the soft, starchy component cake flour naturally contains, diluting the protein load without changing the flavor. The cup-for-cup trick has been around long enough that Cook’s Illustrated, Serious Eats, and America’s Test Kitchen have all published versions of it.
The 1-Cup Ratio Substitution, Every Time
For every 1 cup of cake flour a recipe calls for, measure 1 cup of all purpose flour, remove 2 tablespoons of that flour, and replace those 2 tablespoons with 2 tablespoons of cornstarch. That single swap gets the protein close enough to real cake flour for almost any delicate bake.
If a recipe asks for 2 cups of cake flour, scoop 2 cups of all purpose flour, remove 4 tablespoons total, and stir in 4 tablespoons of cornstarch. Scale the same way for any odd amount, and the math stays predictable every time.
Sifting Together Is Not Optional
Both ingredients need to be sifted together at least three times so the cornstarch distributes evenly through the flour. Skipping the sifting leaves pockets of pure cornstarch that throw off texture and leave a faint starchy taste where they land.
Even with a good blend, how you measure it determines whether the texture holds up.
Tip: sift onto a sheet of parchment, then fold the parchment and pour the blend into your mixing bowl. You lose less to the counter and the blend stays aerated.
Measuring by Weight Beats Measuring by Cup
Volume measurements drift more than most bakers realize. One cup of all purpose flour weighs about 125 grams while one cup of cake flour weighs about 114 grams, so a cup-for-cup swap can quietly overshoot the flour load before you even add the cornstarch.
The Gram-Based Swap
On a kitchen scale, 100 grams of all purpose flour plus 14 grams of cornstarch equals roughly 1 cup of cake flour. Use that ratio as your baseline, then multiply out for any recipe size.
| Cake flour called for | All purpose flour | Cornstarch |
|---|---|---|
| 1 cup (~114 g) | 100 g (about ¾ cup + 2 tbsp) | 14 g (about 2 tbsp) |
| 1¾ cups (~200 g) | 175 g | 25 g |
| 2 cups (~228 g) | 200 g | 28 g |
| 3 cups (~342 g) | 300 g | 42 g |
Why Scooping Breaks the Math
Scooping flour with the measuring cup packs in 15–20% more than spooning and leveling, silently breaking the substitution. A packed cup of all purpose can carry 25 extra grams of flour, and that overflow shows up as a dry, dense crumb that no amount of cornstarch can rescue.
The fix takes ten seconds. Stir the flour, spoon it loosely into the measuring cup, then sweep the back of a butter knife across the top to level it. A kitchen scale removes the guesswork entirely and gives the same result every time you bake, which is the real reason serious bakers own one.
Where the Substitute Shines and Where It Falls Short
The all purpose plus cornstarch blend works beautifully in some bakes and ruins others, so picking the right recipe matters more than measuring precision.
Bakes That Love the Swap
- Pound cakes: their dense, buttery crumb was designed for low-protein flour, so the swap matches their original intent.
- Sponge and chiffon cakes: rely on egg foam over gluten, so the lower-protein blend supports a lighter rise.
- Layer cakes: turn out softer and less crumbly when the protein load drops closer to cake flour’s range.
- Light sugar cookies and snickerdoodles: keep their tender bite instead of turning snappy.
- Pancakes and muffins: benefit from the softer crumb the blend produces.
Bakes That Need Real Cake Flour
- Angel food cake: collapses when protein drops below what real cake flour delivers, so leave it alone.
- Bread, bagels, and pizza dough: depend on gluten structure for rise and chew, which cornstarch dilutes.
- Puff pastry: needs those strong gluten layers to trap steam, so the swap works against you.
- Any laminated dough: requires the elasticity that lower-protein blends cannot supply.
| Bake type | AP + cornstarch works | Stick with real cake flour |
|---|---|---|
| Pound cake | Yes | Optional |
| Sponge / chiffon | Yes | Best |
| Light sugar cookies | Yes | Optional |
| Muffins / pancakes | Yes | Optional |
| Angel food cake | No | Yes |
| Bread, bagels, pizza | No | Use bread flour |
Pastry Flour as a Shortcut
Pastry flour is a near-drop-in stand-in for cake flour if it happens to be in the pantry, requiring no cornstarch. It carries about 8–9% protein, lands right between cake and all purpose, and produces a tender crumb without any blending step at all.
Once the blend exists, keeping it fresh is the next practical hurdle.
Storing the Homemade Blend so It Stays Fresh
Pre-mixed batches keep in an airtight jar at room temperature for up to three months, which is long enough to ride out a couple of cake-filled weekends. A mason jar with a tight lid or a snap-seal plastic container both work fine.
Why the Seal Matters More Here
Cornstarch absorbs moisture from the air, making a tight seal more important than with plain flour. A loose lid lets humidity in, the cornstarch clumps, and the blend turns lumpy inside a week or two.
Heads up: a clump-free jar feels light and silky when you tip it. If the blend packs down or forms little rocks, sift it twice before measuring or the cornstarch pockets will wreck the next bake.
Give the jar a quick sift before each use since the blend tends to settle during storage, and label the jar with the date it was mixed so older batches get used first. A strip of masking tape on the lid with the date in marker takes care of it.
Troubleshooting Texture When the Substitute Misbehaves
A bad bake tells you exactly which step went sideways, and the symptoms are specific enough to diagnose without rerunning the recipe blind.
Too Dense or Too Tough
A dense or tough crumb usually points to over-measured flour or cornstarch that was not fully sifted in. Recalibrate by switching to gram measurements and re-sifting the blend before the next attempt, then mix the batter only until the dry streaks disappear.
Gummy or Pasty Center
A gummy or pasty texture often signals too much cornstarch in the mix, frequently from compressed measuring. If the spooned level of cornstarch crept past the 2 tablespoon mark, the crumb loses structure and sets up pasty in the middle, so weigh the cornstarch next time and sift it in.
Domed Top With a Crack Down the Middle
Cakes that dome and crack in the center suggest the batter was overmixed once the flour went in, which overdeveloped the very gluten the swap was trying to soften. Fold the dry ingredients in by hand with a spatula and stop the moment no streaks of flour remain.
Warning: a sunken middle on a sponge or chiffon cake almost always means the egg foam deflated before the bake, not a flour problem. Whip the whites to soft peaks and bake immediately for a clean rise.
Bottom Line
One cup of all purpose flour minus 2 tablespoons plus 2 tablespoons of cornstarch, sifted together three times, gives you a cake-flour stand-in that handles most delicate baked goods with confidence. Measure by weight when the recipe allows, skip the swap for anything that needs real gluten strength, and store the blend in a tight jar so the cornstarch stays dry and clump-free.
FAQ
Can you substitute all purpose flour for cake flour in a recipe?
Yes, with the 2-tablespoon cornstarch swap per cup, the substitute works in most delicate baked goods like pound cake, layer cake, and muffins. Avoid it for angel food cake, bread, and pizza dough, which depend on real cake flour’s protein or on stronger gluten networks.
How much all purpose flour equals one cup of cake flour?
Subtract 2 tablespoons of all purpose flour from a full measure, add 2 tablespoons of cornstarch, and you have one cup of cake flour. By weight, that is 100 grams of all purpose flour and 14 grams of cornstarch blended and sifted together three times.
What is the easiest way to make cake flour from all purpose flour?
Measure 1 cup of all purpose flour, remove 2 tablespoons, stir in 2 tablespoons of cornstarch, and sift the two together at least three times. The sift is what distributes the cornstarch evenly, so do not skip it.
Does the cornstarch trick actually work for replacing cake flour?
It works because cornstarch displaces some of the higher-protein flour without adding flavor, dropping the effective protein close to cake flour’s 7–9% range. The texture comes very close for pound cakes, layer cakes, muffins, and light cookies.
How much cornstarch do I add to all purpose flour to make cake flour?
Add 2 tablespoons of cornstarch per 1 cup of all purpose flour, after removing 2 tablespoons of that flour. The 2-to-2 swap keeps the total volume the same while trimming the protein load.
Will my cake be tough if I use all purpose flour instead of cake flour?
Straight all purpose flour, used cup for cup, does make a cake tougher because the extra protein forms more gluten during mixing. The cornstarch swap pulls the protein back down so the crumb behaves closer to cake flour.
