Cake Flour Substitute - When to use it (and When to Not!)

June 17, 2020

Written By: Adriana

Using cake flour is one of the easiest ways to give your cakes an airy and lighter crumb. As good as it is to have, it can be sometimes difficult to find. Or perhaps you’ve just run out. Luckily there is a homemade substitution, and I’ve used this homemade version of cake flour with great success in my cakes.

To make cake flour, substitute 15% the total weight of all purpose flour with corn or potato starch. Using volume, this is 2 ½ TB for every cup, or 18g for 120g by weight. This is best for American-style butter cakes, as fine crumbed lighter European-style cakes are best with commercial cake flour.

As easy as this cake flour substitution is, it’s important to know when and how to use it. In addition, there are many types of flours that are out there for home bakers. As one of the core ingredients in baking cakes, it’s worthwhile to get a little understanding on how the type of flours and starches will impact your finished cake.

Some quick background on flours

For basic baking you will rely on mostly all purpose flour. I baked with all-purpose flour for many years and it was fantastic. As your baking starts to get a little more specific and you start to learn a little more about what types of textures you want to achieve in your baking, you will want to expand your flour collection.

In my pantry, I always have all-purpose flour, bread flour, and cake flour on hand. I also love using pastry flour for my pies, but you can easily make that using all-purpose flour and cake flour. (More on that later!)

It's important to have different flours because they all contain various amounts of protein in them. The protein content is important because it will affect the textures and ways that your goodies will bake. The most important proteins (in flours and starches) to consider in terms of making cakes are the ones we categorically refer to as “gluten”, but there are a couple important proteins that actually make up gluten.

The two main protein players that you want to remember for your baking are gliadin and glutenin. Both these protein molecules, when introduced to certain baking environments (such as kneading by us), will bind to each other and form long strands of gluten.

Gluten is that chewy texture that you want in pizza crusts and french breads. We do not, however, want any trace of that texture in our cakes.

We want a light and airy melt-in-your-mouth cake with no chew. We get this by using flours with lower gluten content. We want just enough protein to give us structure, but not so much that it will form long chewy strands in the batter when we mix it.

Type of flour/starch Protein content (%)
Vital gluten 70-85
Bread 12-13
All-purpose 11-12
Pastry 8-9
Cake 7-8
Cornstarch/Potato starch 0

Notice how cornstarch has no protein content.

So to make cake flour, what we’re effectively doing is replacing a portion of protein containing flour with a starch that has no protein in it at all. This will help us lower the final protein (gluten) content of the flour that we need.

Using this method, we can pretty much make almost every flour we need.

For this reason (and because I am a crazy home baker), I always have these flours in my pantry:

  • Vital gluten
  • All purpose Four
  • Cake Flour
  • Cornstarch

I can usually make almost any flour I need on the spot using a combination of these flours. In this post, we’re covering cake flour, so I’ll show you how to make that.

The math behind homemade cake flour

(You can skip this part if you’re not into math. I’ll give you exact measurements in the next section.)

A common substitute floating around the webs states that you can sub out 2 TB of all-purpose flour with 2 TB of cornstarch, which is not accurate enough for me.

I have used the more widely accepted accurate number of 15% w/w (weight by weight), which is 18g for every 120 g of flour. Converted to volume, this is approximately 2.5 TB of cornstarch out of every cup of flour. This of course varies on the brand of flour, but I always approximate one cup of flour to 120g.

As the particular protein content of one brand of flour to another, this 15% is a little less than half my calculated amount of a 33% replacement using the chemical dilution formula C1V1 = C2V2.

My guess for the lower replacement of flour is because perhaps the amount of gluten indicated in an all-purpose flour contains far less gluten molecules than other types of starches.

Therefore, less replacement using cornstarch is actually necessary than would be indicated if the numbers were entirely accurate.

That, or cutting with that much potato or cornstarch is somehow inhibitory to the cake crumb. Stay posted as I will report on this later with my findings.

How to make cake flour substitute

You can use bleached or unbleached flour, but keep in mind that most commercial cake flours have bleached flour in them. You can read about the specifics of bleached vs. unbleached on cake crumb here, but the gist of it is that unbleached gives you a coarser textured crumb, much like cornmeal.

Unbleached works just fine though, and is in fact what I use every day (because I can get it in bulk at Costco for cheap :) ) but if you are into, like, the perfect cake crumb for a worldwide cake competition, you will likely need to use bleached flour.

For your gluten-less starch, it’s recommended to use corn or potato starch. The post from Rose Levy that I linked earlier also goes into the trials of using both starches.

Generally speaking, both are ok, although potato starch does seem to pair better with unbleached flour. The one caveat here is that potato starch is darn hard to find. I almost always use corn starch.

If you use volume (cups and spoons) to measure, you would go about making cake flour like this:

To use the 15% rule, you will need to substitute 2 ½ TB of flour for every cup of flour you use. I would make a large batch of cake flour, keep it in a container, and measure cake flour directly out of that container.

Say you wanted to make a 3 cup batch. Measure out 3 cups into a very large mixing bowl. Scoop out 7.5 TB (or ½ cup with 1.5 teaspoons removed) from your bowl. Add back in 7.5 TB of corn or potato starch in the large mixing bowl. Whisk this for at least 30 seconds; set a timer if you need to, but whisk no less than 30 seconds. (Sifting is not as effective, so don’t waste your time with that.) Store in an airtight container or measure from there.

If you bake by weight, you would go about making cake flour like this:

Every cup of flour is approximately 120g, so for every cup use 102g of all purpose and 18g of corn or potato starch. I’m a by-weight baker, so I just measure this on the fly when baking. I have all these numbers memorized, and so if I’m out of cake flour I usually just calculate my flour weights as I need them in my head.

Substituted cake flour works best with most (but not all) cakes

Commercial cake flour is milled so that the flour particles are very fine. It also is bleached, and so has a particular acidic taste and batter. Just doing a plain replacement of some of the all purpose with corn or potato starch is not going to replace all of the large particles or alter the taste and pH.

Some cakes are really best when made with commercial cake flour, as there is no “homemade” way of replicating the texture and taste.

In that case, I would not use this substitute if I were making very finely textured and airy cakes. These include the European style ones where you have to whip up egg whites for structure.

In general this is a list that I follow for cake and flour pairings:

Chocolate - all purpose

Vanilla Butter - cake flour/cake flour substitute

Genoise - cake flour only

Chiffon - cake flour only

Sponge - cake flour only

Angel Food cake - cake flour only

Most of the cakes on my site are butter-based American style cakes (the top two cakes) that use baking soda/baking powder and leaveners.

However, I will always indicate which type of flour is best to use and if any substitutions can be made.

Hi Everyone, I'm Adriana

... the nerdy baker behind the videos and recipes here. I coded this site to not only share my recipes with you but also to build some helpful tools for bakers.

Read more here!
Sign up for freshly baked news:

I bake for these charities - check them out!

Baking adventures on Instagram...