Caster Sugar vs Granulated Sugar: How Crystal Size Affects Baking

Sugar looks simple sitting in a pantry, but once you start baking with intention, the differences matter more than most people expect. The choice between caster sugar and granulated sugar can quietly shape texture, crumb, sweetness distribution, and even how a recipe behaves before it ever reaches the oven.

If you have ever followed a recipe exactly and still ended up with a cake that felt slightly gritty, cookies that spread differently than expected, or a meringue that refused to smooth out, sugar crystal size may have been the reason. This is where the conversation around caster sugar vs granulated sugar becomes practical rather than theoretical.

Both sugars start from the same place. Both are white sugars made from refined sucrose. What separates them is not chemistry, but physical structure. That structural difference affects how sugar dissolves, how it incorporates into fats and liquids, and how it behaves under heat. Understanding those differences gives bakers more control, not more rules.

This guide breaks down what caster sugar and granulated sugar are, how they behave in real baking situations, when one performs better than the other, and how to substitute confidently when you only have one on hand.

Caster sugar is white sugar with very fine crystals. It is finer than standard granulated sugar but not ground into a powder. The texture is often compared to fine sand rather than dust. It pours freely, does not clump, and still has visible grains when examined closely.

In some regions, especially outside the United States, caster sugar is the default sugar used in baking. In American kitchens, it is often labeled as superfine sugar, baker’s sugar, or bar sugar. Regardless of the name, the defining feature remains the same: smaller crystal size.

Because the crystals are smaller, caster sugar dissolves more quickly than granulated sugar. That faster dissolving behavior changes how it performs in batters, foams, creams, and liquids. It incorporates smoothly into mixtures without leaving undissolved grains behind.

Caster sugar is commonly used in recipes where texture needs to stay light and uniform. It performs especially well in whipped egg whites, whipped cream, sponge cakes, and recipes that rely on sugar dissolving without heat.

Granulated sugar is standard white table sugar. It has larger, more coarse crystals than caster sugar. The grains are uniform and clearly defined, which is why they feel slightly gritty when rubbed between fingers.

Granulated sugar dissolves more slowly than caster sugar. In hot liquids or during long mixing, this difference may not matter much. In cold mixtures or short mixing processes, the difference becomes noticeable.

This slower dissolving behavior is not a flaw. In many cases, it is useful. Granulated sugar interacts with fat differently during creaming, contributes to structure in cookies, and can create texture where a little resistance or crunch is desirable.

Granulated sugar is widely used in everyday baking, cooking, sauces, and confectionery. It is the most common sugar found in home and commercial kitchens, which is why understanding how it compares to caster sugar is useful rather than academic.

When comparing caster sugar vs granulated sugar, the core difference is crystal size. Everything else flows from that single factor.

Smaller crystals mean more surface area relative to volume. More surface area allows sugar to dissolve faster when it comes into contact with liquid. Larger crystals take longer to dissolve and may remain intact longer during mixing.

This difference affects several aspects of baking:

• How quickly sugar dissolves in cold or room temperature mixtures
  
  

• How smoothly sugar incorporates into fats during creaming
  
  

• Whether undissolved sugar remains visible after baking
  
  

• How texture develops in cookies, cakes, and foams
  
  

The sugar itself does not change flavor. What changes is how evenly that sweetness spreads throughout a recipe and how it interacts with other ingredients.

Dissolving speed is one of the most practical distinctions between caster sugar and granulated sugar.

Caster sugar dissolves very quickly. This makes it ideal for recipes where sugar needs to disappear into a mixture without heat or extended mixing. Examples include whipped cream, meringues, mousses, syrups, and cocktails. In these cases, undissolved sugar can leave a grainy mouthfeel or prevent proper structure from forming.

Granulated sugar dissolves more slowly. In batters that are mixed briefly or contain minimal liquid, some sugar crystals may remain intact longer. This can show up as a slightly speckled appearance in cakes or a more textured bite.

In recipes where sugar dissolves fully during baking or cooking, such as breads or long-simmered sauces, the difference in dissolving speed becomes less noticeable.

Caster sugar is often preferred for cakes that aim for a fine, even crumb. Because it dissolves quickly, it blends smoothly into batters and helps produce a lighter texture. Cakes made with caster sugar tend to have a more uniform interior without visible sugar granules.

Granulated sugar can still be used in cakes, but it may require longer creaming or mixing to achieve similar results. If not fully dissolved, granulated sugar can leave a slightly coarser texture or subtle speckling on the surface or crumb.

Neither result is inherently wrong. Some cakes benefit from a bit of structure and texture. The choice depends on the desired outcome.

Granulated sugar often performs well in cookies, especially when chewiness or crunch is desired. The larger crystals contribute to structure and can caramelize during baking, affecting spread and texture.

Caster sugar produces a finer, softer cookie. When used alone, it may lead to cookies that spread differently or lack the subtle bite that granulated sugar provides.

Many cookie recipes use a blend of sugars to balance texture. Understanding crystal size helps explain why those combinations work.

Caster sugar excels in meringues, pavlova, and whipped egg whites. Its fine crystals dissolve quickly into the foam, allowing proteins to stabilize properly without graininess.

Granulated sugar can be used for meringues, but it requires more patience. Mixing at a lower speed for longer allows the sugar time to dissolve. Without that adjustment, the finished meringue may feel gritty or fail to achieve a smooth surface. The same principle applies to whipped cream and other foamed mixtures.

Granulated sugar is often favored for caramel and toffee. Its larger crystals dissolve predictably when heated and are less likely to crystallize prematurely when handled correctly.

Caster sugar can be used for caramel, but the faster dissolving behavior does not offer a clear advantage in high heat applications.

Caster sugar dissolves easily in cold liquids, making it useful for cocktails, iced drinks, and syrups where heat is not applied. Granulated sugar struggles in these situations unless given time or agitation. This is one reason caster sugar is sometimes referred to as bar sugar.

Creaming butter and sugar is a mechanical process where sugar crystals help incorporate air into fat. Both caster sugar and granulated sugar can perform this role, but they behave slightly differently.

Granulated sugar’s larger crystals can create air pockets as they cut into butter, contributing to structure. This can be helpful in cookies and denser baked goods.

Caster sugar integrates more smoothly and dissolves more quickly, leading to a finer texture. The creaming process may take slightly less time, and the mixture often looks smoother sooner.

If using granulated sugar in place of caster sugar, extending the creaming time allows more crystals to dissolve and improves consistency.

In most cases, yes. Caster sugar and granulated sugar are interchangeable with small adjustments.

If a recipe calls for caster sugar and only granulated sugar is available, there are two practical options:

1. Mix longer. Extended creaming or mixing gives granulated sugar time to dissolve.
   
   

2. Make your own caster sugar by briefly pulsing granulated sugar in a food processor until it becomes superfine but not powdery.

If a recipe calls for granulated sugar and caster sugar is used instead, the result may be slightly finer or softer, but usually still successful.

What matters most is understanding how the sugar is meant to behave in that recipe. Sugar is not just a sweetener. It affects texture, structure, and mouthfeel.

Making caster sugar at home is simple and reliable. Granulated sugar can be transformed into superfine sugar using basic equipment.

Add granulated sugar to a food processor, blender, or clean coffee grinder. Pulse briefly until the crystals become finer. The goal is a texture that pours freely and feels smooth, not a powder that clumps.

Overprocessing turns sugar into powdered sugar, which behaves very differently in baking. Short pulses and frequent checks help avoid that.

Homemade caster sugar performs similarly to store bought versions in most recipes.

In commercial and professional baking environments, consistency matters. Caster sugar is often chosen for recipes where predictable dissolving and smooth texture are priorities.

Granulated sugar remains widely used because of its versatility, availability, and performance in a broad range of applications. Many bakeries stock both and choose based on the specific product being made.

Neither sugar is superior in all situations. Each serves a different purpose.

The table below shows how caster sugar and granulated sugar differ in everyday baking.

The difference between caster sugar and granulated sugar matters most when sugar does not have time or heat to dissolve fully. This includes:

• Whipped egg whites
  
  

• Cold liquids
  
  

• Short mixing processes
  
  

• Delicate batters
  

In long bakes or cooked applications, the difference becomes less pronounced.

Understanding when crystal size matters allows bakers to adapt confidently rather than follow rigid rules.

Instead of asking which sugar is better, it helps to ask what result you want.

If the goal is smoothness, lightness, and even texture, caster sugar often performs well.

If the goal is structure, chew, or subtle crunch, granulated sugar may be the better choice.

Most baking mistakes involving sugar are not caused by choosing the wrong type, but by not adjusting technique when substituting.

• Caster sugar and granulated sugar are the same sugar with different crystal sizes
  
  

• Caster sugar dissolves faster and creates smoother textures
  
  

• Granulated sugar dissolves slower and can add structure or texture
  
  

• Both sugars can usually be substituted with small technique adjustments
  
  

• Understanding crystal behavior gives bakers more control over results
  

Q: What is the main difference between caster sugar and granulated sugar?
 A: The difference between caster sugar and granulated sugar is crystal size, with caster sugar having finer grains that dissolve more quickly.

Q: Can I use granulated sugar instead of caster sugar in baking?
 A: Granulated sugar can replace caster sugar if you mix longer or allow more time for the sugar to dissolve fully.

Q: Why does caster sugar work better for meringues?
 A: Caster sugar dissolves quickly into whipped egg whites, which helps create a smooth and stable foam.

Q: Does caster sugar make cakes lighter?
 A: Caster sugar can produce a finer crumb because it incorporates smoothly into batter without leaving undissolved crystals.

Q: Is caster sugar the same as powdered sugar?
 A: Caster sugar is not powdered sugar, as powdered sugar is ground much finer and behaves differently in recipes.

Q: Can I make caster sugar at home?
 A: Caster sugar can be made by pulsing granulated sugar briefly until the crystals become superfine but not powdery.

Q: Why do cookies sometimes use granulated sugar?
 A: Granulated sugar contributes texture and structure to cookies and can affect chewiness and spread.

Q: Does caster sugar dissolve in cold drinks?
 A: Caster sugar dissolves more easily in cold liquids than granulated sugar due to its finer crystals.

Q: Will using the wrong sugar ruin a recipe?
 A: Most recipes tolerate sugar substitutions if mixing technique and timing are adjusted accordingly.

In day-to-day baking, the difference between caster sugar and granulated sugar usually shows up in small, practical ways. A cake that feels right but looks slightly uneven on the surface. A whipped cream that sweetens evenly but never quite turns smooth. A meringue that sets, yet keeps a faint graininess no matter how long it whips. None of these ruin a recipe, but they are the kinds of results that make you pause and wonder what changed.

This is where crystal size starts to matter. Caster sugar tends to blend in quickly and quietly, especially in mixtures that do not rely on heat to melt the sugar. Whipped egg whites, lighter batters, and cold liquids all benefit from sugar that dissolves fast and evenly. You spend less time compensating during mixing, and the texture settles where you expect it to.

Granulated sugar shows its strengths in different places. Its larger crystals can add structure and texture, which is useful in cookies, bars, and baked goods where a little bite is part of the appeal. In these cases, the sugar does not need to disappear immediately. It has time to dissolve during baking, and the result often feels intentional rather than rough.

When substituting between the two, technique matters more than the label on the bag. If a recipe depends on sugar dissolving early, granulated sugar may need more mixing time or a slower approach in whipped mixtures. If the recipe allows sugar to dissolve later, during baking or cooking, the difference between the two becomes much less noticeable. Paying attention to that moment where sugar meets the rest of the ingredients usually tells you which one will be easier to work with.