What Is Cake Flour? The UK Baker's Guide to Lighter, Fluffier Cakes

If you've ever followed a recipe and wondered, "wait, do I actually need cake flour" - or quietly substituted plain flour and hoped for the best - you're not alone. Cake flour is one of those ingredients that crops up in recipes (often American ones) and leaves UK bakers scratching their heads. Is it the same as self-raising? Can you swap it for plain flour? And does it actually make a difference? 

The short answer: yes, it absolutely does - and once you understand why, you'll never reach for the wrong bag again. Whether you're chasing that impossibly light Victoria sponge or baking the dreamiest layer cake, understanding cake flour is your shortcut to a softer, more tender crumb. Let's get into it.

Cake flour is a finely milled, low-protein wheat flour specifically designed for baking delicate cakes and baked goods. It's made from soft winter wheat and milled to an extra-fine texture - finer than plain flour and far, far finer than bread flour.

In terms of protein content, cake flour typically contains around 7–9% protein, compared to 10-12% in regular plain (all-purpose) flour. That might not sound like a dramatic difference, but in baking, those few percentage points have a huge impact on your final result.

In the UK, you might also see cake flour sold under the name sponge flour or sponge cake flour - same thing, different label. It's not as widely stocked as plain or self-raising flour in supermarkets, which is why many home bakers end up making their own substitute (more on that below).

Importantly, cake flour contains no raising agents. It's a pure flour - nothing added. This gives you full control over your leavening, which professional bakers love.

Here's the baking science bit - and it's actually pretty fascinating once it clicks. When you mix flour with liquid, proteins in the flour (called glutenin and gliadin) combine to form gluten. The more protein in your flour, the more gluten can develop - and the chewier, more structured your bake will be.

For bread, that's exactly what you want. A strong gluten network gives bread its satisfying chew and structural integrity. But for a delicate sponge cake? Too much gluten means a tough, dense, rubbery result. Nobody wants that!

This is where cake flour earns its keep. Its lower protein content means less gluten forms during mixing, resulting in a:

• Softer, more tender crumb

• Lighter, airier texture

• Finer, more even crumb structure

• Delicate mouthfeel that melts on the tongue

The extra-fine milling also plays a role. Because cake flour is ground so finely, it absorbs liquids more readily and distributes throughout your batter more evenly - giving a more consistent bake with a smoother texture.

Let's clear up the most common points of confusion once and for all. Here's how the main flour types compare:

The key takeaway: cake flour is NOT the same as self-raising flour. Self-raising flour already contains baking powder (and sometimes salt), so it raises your cake for you. Cake flour is a plain, low-protein flour with no added leavening - you add your raising agents separately.

Can you use plain flour instead of cake flour? You can - but the result won't be quite as light and tender. Plain flour's higher protein content means slightly more gluten development, which gives a slightly denser crumb. For a showstopper sponge, that difference matters.

So we know cake flour is low in protein and finely milled - but what does that actually translate to in your finished bake? Quite a lot, as it turns out.

1. A Softer, More Tender Crumb

The reduced gluten formation means your cake has a soft, almost pillowy texture. Cut into a cake made with proper cake flour and you'll notice the difference immediately - it's cloud-like, with a fine, even crumb that practically dissolves on the tongue.

2. Better Moisture Absorption

Because cake flour is so finely milled, it absorbs moisture from eggs, butter, and milk more efficiently. This means the fat and liquid are better distributed throughout the batter, which contributes to a richer, more moist cake that stays fresh for longer.

3. A Lighter Rise

With less gluten to weigh it down, your cake batter can rise more freely and evenly. Combined with the right amount of baking powder or self-raising agents, cake flour gives you cakes that rise beautifully tall without sinking in the middle.

4. A More Professional Finish

This is the one the professionals don't always tell you about. Cake flour gives your bakes that bakery-quality crumb you see in high-end patisseries - fine, consistent, and utterly luxurious. It's one of the secrets behind truly exceptional cakes.

Cake flour isn't the right choice for every bake - but for certain types of cake, it's a game-changer. Here's when it really shines:

Cake flour is perfect for:

• Victoria sponge and classic British sponge cakes

• Layer cakes and celebration cakes

• Chiffon cakes and angel food cakes

• Delicate cupcakes with a fine crumb

• Madeira cake

• White cakes and vanilla butter cakes

• Swiss roll

Stick to plain or strong flour for:

• Bread and enriched doughs

• Shortcrust and flaky pastry (plain flour works best here)

• Biscuits and cookies that need structure

• Pizza bases

• Banana bread and loaf cakes where a denser texture is desirable

If you're making our Perfect Vanilla Sponge Cake Recipe, swapping in cake flour (or a homemade cake flour substitute) will give you an exceptionally tender crumb - and let's be honest, isn't that exactly what a sponge should be?

Since cake flour can be tricky to track down in UK supermarkets, many bakers make their own version at home - and it works brilliantly. The trick is to lower the protein content of plain flour using cornflour (cornstarch), which contains no gluten-forming proteins at all.

The Method

You'll need:

• Plain flour

• Cornflour (cornstarch)

For every 100g of cake flour needed:

• Measure out 100g of plain flour

• Remove 1 tablespoon (about 8g) of the plain flour

• Replace with 1 tablespoon (about 8g) of cornflour

• Sift together thoroughly - at least twice - to make sure they're fully combined

• Use immediately or store in an airtight container

The sifting step is important here, not just for mixing but because it also aerates the flour mixture, further mimicking the fine texture of shop-bought cake flour. If your recipe uses cup measurements: for every 1 cup of cake flour, use 3/4 cup + 2 tablespoons of plain flour plus 2 tablespoons of cornflour.

This substitute gets you very close to the real thing - and for many recipes, you won't be able to tell the difference. It's a staple trick worth keeping up your sleeve, along with the rest of your essential baking kit.

Cake flour isn't stocked in every supermarket, but it's more available than it used to be. Here's where to look:

• Specialist baking shops and online baking retailers

• Waitrose and Ocado occasionally stock it under the 'sponge flour' name

• Amazon UK stocks several brands including Shipton Mill and various US imports

• Whole Foods Market and independent health food shops sometimes carry it

When buying cake flour, check the protein content on the label - you're looking for anything under 9%. Some products labelled 'sponge flour' in the UK fall in the 9-10% range, which is lower than plain flour but not quite as low as dedicated cake flour. Either will give you a noticeably more tender result than standard plain flour.

1. Always sift it. Cake flour can clump due to its fine texture. Sift it at least once before adding to your batter - twice if you want to be thorough.

2. Measure accurately. Because cake flour is so fine, it can compact in a measuring cup. Use the spoon-and-level method (spoon flour into the cup, then level off) or better yet, weigh it in grams.

3. Don't overmix. Even with low-protein cake flour, overmixing once your wet and dry ingredients combine will develop gluten. Mix until just combined for the tenderest result.

4. Room temperature ingredients matter. Cake flour works best when your butter, eggs and dairy are all at room temperature. Cold ingredients can cause the batter to curdle, which affects the final texture.

5. Trust the sift. We know we've said it already, but it really is that important. Properly sifted cake flour is one of the easiest things you can do to upgrade your baking game - and it takes about 30 seconds.

Is cake flour gluten free?

No. Cake flour is made from wheat, so it does contain gluten - it simply contains less gluten-forming protein than plain flour. It is not suitable for anyone with coeliac disease or a gluten intolerance. For gluten-free baking, look for dedicated gluten-free flour blends.

Can I use cake flour in brownies?

You can, but we'd generally advise against it for brownies. The fudgy, dense texture that makes a great brownie actually benefits from a bit more structure. Cake flour would make your brownies too delicate and crumbly. Plain flour is the better choice here.

Does cake flour expire faster than plain flour?

Cake flour has a similar shelf life to plain flour - typically 12 to 18 months if stored in a cool, dry, airtight container away from direct sunlight. The extra-fine milling doesn't affect how quickly it goes stale.

Does cake flour expire faster than plain flour?

In the UK, cake flour is sometimes sold as 'sponge flour' or 'sponge cake flour'. It refers to the same low-protein, finely milled flour designed for delicate baked goods. Because it's less commonly stocked than in the US, many UK bakers make their own version using plain flour and cornflour, as described above.

• Cake flour is a low-protein (7–9%), extra-finely milled flour made from soft winter wheat
  
  

• Its lower protein content means less gluten forms, resulting in a softer, more tender crumb
  
  

• Cake flour is NOT the same as self-raising flour - it contains no raising agents
  
  

• In the UK it may be labelled 'sponge flour' or 'sponge cake flour'
  
  

• You can make a great substitute by combining plain flour with cornflour (remove 1 tbsp flour per 100g, replace with 1 tbsp cornflour, sift well)
  
  

• It's best used for delicate cakes: Victoria sponge, layer cakes, chiffon, cupcakes, madeira
  
  

• Always sift cake flour and avoid overmixing your batter for the best results