What Is Caster Sugar? Does It Really Make a Difference in Baking?

This superfine sugar is particularly popular in the U.K.

December 17, 2021
Photo by Julia Gartland

When our Baking Club focused on Yotam Ottolenghi and Helen Goh's cookbook Sweet: Desserts from London's Ottolenghi, members with the UK version kept noticing that the vast majority of the recipes call for caster sugar.

Caster sugar goes by a variety of names, including castor sugar, baker’s sugar, and superfine sugar, the last of which alludes to what exactly it is: a finer granulated sugar. If a grain of granulated sugar is big and a grain of powdered sugar is tiny, caster sugar would be somewhere in between.

On the top sit different sugars; on the bottom sit their powdered counterparts. The caster versions of these sugars would be right in the middle. Photo by Mark Weinberg

What is Caster Sugar?

Caster sugar goes by a variety of names, including castor sugar, baker’s sugar, and superfine sugar, the last of which alludes to what exactly it is: a type of superfine sugar. Like if regular old white sugar got put into the food processor for a minute or two. If a grain of granulated sugar is big and a grain of confectioners’ sugar is tiny, caster sugar would be somewhere in between. It’s ideal for dissolving in ice cold beverages (like some added sweetness for an iced coffee or iced tea), as well as seamlessly blending into frosting, glazes, and whipped cream. Caster sugar brings plenty of sweetness without any of the textural graininess that coarser types of sugars often contribute. There’s a chance you’ll find caster sugar in some regular grocery stores, but any specialty baking shop or big-box online retailer is guaranteed to carry it.

As for how it compares to other types of sugar, it’s not as fine as powdered sugar aka icing sugar aka confectioners’ sugar. Whereas those types of sugar are true powder (closer to cornstarch or flour), caster sugar still has a grain-like texture that you can feel between your fingers.

Types of Caster Sugar

Just like regular granulated sugar and brown sugar, you’ll find both white caster sugar and golden caster sugar. Golden caster sugar is made with natural, unrefined cane sugar, whereas regular caster sugar is refined for that pure white color. You can use them interchangeably…for the most part. Think of them, again, as superfine versions of regular sugar and brown sugar. They’ll work as seamless substitutes for one another in cake and cookies, but you probably wouldn’t use brown sugar in a recipe for vanilla buttercream; same goes for golden caster sugar.

After learning about the difference between regular granulated sugar and caster sugar, Food52’s community member Eliza Triggs made back-to-back batches of Ottolenghi and Goh’s Cranberry Almond Cookies and found that using caster sugar did make a noticeable difference in the appearance and taste:

The iced cookie on the bottom is made with regular sugar; it looks and tastes drier and denser (although it’s definitely a tasty biscuit). The one on the top is made with caster sugar, and (although it’s still crumbly) is softer, lighter, and more buttery.

Helen Goh explained that caster sugar appears in so many of the recipes in Sweet because: "In the UK, we use it for most baked goods, especially if it is being creamed/beaten with butter for making cakes, or for whisking with egg whites for meringues."

While caster sugar is readily available in the UK, Baking Club members in the United States have had trouble locating it, and when they can get their hands on it, they find it is priced much higher than regular granulated sugar. Luckily, Goh provided the group with three strategies to still get optimal outcomes in their baked goods. Here’s how to achieve the best baked goods with caster sugar.

How to Bake With Caster Sugar

1. Start with cooler than room temp butter.

Goh explains that if you are creaming sugar with butter (for cakes or cookies, for example), starting with firmer butter allows you to cream the two together for a bit longer without it turning greasy, adding:

Over-creaming can result in an oily, dense cake because the butter has essentially melted. Similarly, under-creaming can result in a dense, dry cake, because the butter and sugar have not had enough air incorporated into it, and the sugar granules remain large, so the cake/crumb will be coarse and heavy.

2. Whisk egg whites on a lower speed.

If you're combining sugar and egg whites for something like a meringue, Goh suggests whisking the egg whites and granulated sugar together on a slightly lower speed so the sugar granules have more time to dissolve, adding:

One of the ways you can tell if your meringue is ready for the oven is if you can barely feel the sugar granules between your thumb and forefinger. I have seen a few 'speckled' pavlovas which look like undissolved sugar granules.

3. Make your own caster sugar.

You can also skip the workarounds and cut to the chase by making your own caster sugar. Simply process regular granulated sugar in a food processor, high-powered blender, or (clean) coffee grinder until the sugar granules are smaller. (Just keep an eye on it—if you process it too long you'll end up with homemade powdered sugar instead.) Goh notes that the granules won't be as uniformly sized as the store-bought variety, but says that it will work fine.

Once you've made a batch of caster sugar, here are a few recipes to put it to good use:

Caster Sugar Recipes

Lemon Meringue

Combine lemon meringue pie and a pavlova and a layer cake and you end up with something like this. We love the combination of lemon curd and pistachio-y yogurt. Note: It's a hefty project—but well worth it.

Angostura Sugar Cubes

A last-minute two-ingredient host gift (or a party trick for the next time you have people over). All you need are caster sugar and Angostura bitters. We'll bring the champagne.

Raspberry Ripple Sandwich

Yes, toast can and should be called dessert. Do as Nigel Slater does and mash raspberries into oblivion, swirl these into sweetened whipped cream, and plop this cloud on just-toasted bread. In lieu of raspberries, try strawberries, blackberries, peaches, or apricots.

Lemon Tart

It's called lazy for a reason. To make the filling, you add a whole Meyer lemon (yep, rind, pith, and all), sugar, butter, vanilla, and eggs to a blender. Pour this into a tart shell and bake up your new go-to dessert.

Espresso-Walnut Cake

Picture this: Espresso cake layers. Crispy-marshmallowy meringue. Maple syrup–sweetened whipped cream. Serve at the next gathering when you want to dazzle all your friends.

Pomegranate Passion Cake

A sticky, dense almond cake gets upgraded with pomegranate molasses, then topped with sweetened mascarpone and fresh pomegranate seeds.

Frozen Daquiri

White rum, freshly squeezed lime juice, sugar, and ice, blended until slushy and frosty, equal as refreshing a cocktail as any heatwave could hope for. Serve in a glass that makes you smile, with a lime wheel on top.

Crême Brûlée Pie

Just when you thought crême brûlée couldn't be improved upon, it relocates to a flaky pie crust. Sprinkle sugar on top, then torch until your whole kitchen smells like caramel and toffee.

This article was originally published in December 2017. We updated it with even more caster sugar–friendly recipes.

See what other Food52 readers are saying.

  • suzanne
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    Janice Coby
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    Danuta Gajewski
  • littleknitter
I like esoteric facts about vegetables. Author of the IACP Award-nominated cookbook, Cooking with Scraps.


suzanne December 30, 2021
Superfine sugar is readily available in grocery stores in California. C&H sells it as Baker’s Sugar and as Superfine Sugar in various sizes- including the handy half-gallon milk carton size.
StacyT June 23, 2020
What happens if I over-process the sugar and it’s essentially like powdered sugar? How will it affect the cake/cookie/muffin recipe that calls for granulated or superfine sugar?
Janice C. August 1, 2019
What is golden caster sugar? Each time I research it I get a different answer, from dark brown sugar to Turbinado.
Danuta G. March 28, 2018
An fyi for Canadian bakers: fruit sugar is the same as caster sugar. It's a tad more expensive (works out to about $1 more for a 1kg bag) but as someone below mentioned, worth the money in terms of wear and tear on your food processor!
littleknitter December 17, 2017
I lived in the UK for a few years and the granulated sugar over there has much, much larger crystals than US granulated sugar. Domino's granulated sugar is much closer in size to UK caster sugar than it is to UK granulated sugar and is a perfectly fine substitute if you're living in the US.
plevee April 14, 2018
In the Uk sugar is much coarser and salt much finer than in the US.
Ann W. November 9, 2018
I'm an American living in the UK and that's been my observation too: on the fine=>coarse spectrum I would say:

US confectioners'/UK icing
US superfine
UK caster
US granulated
UK granulated
SweetM December 17, 2017
Is C&H Baker’s Sugar the same as caster sugar?
Lindsay-Jean H. December 17, 2017
Yes, caster sugar, castor sugar, baker’s sugar, and superfine sugar are all different names for the same thing!
Leslie B. December 30, 2020
YES and it is readily available in super markets, so I am not sure why the article said it is hard to find ‘caster sugar’ or that it is prohibitively expensive. These are absolutely just different names for the same product... (I am an American who has lived in London for 25 years...)
Gina F. December 16, 2017
I measure dry ingredients by weight. What would 1 cup of caster sugar equal in grams? For granulated sugar, I use 1 cup equals 198 grams. Thanks!!
Lindsay-Jean H. December 17, 2017
I use 200 grams for both 1 cup of regular and caster sugars. Helen Goh weighs 1 cup of caster sugar as 225 grams and 1 cup of granulated sugar as 220 grams.
Victoria C. December 14, 2017
I get India Tree Caster and India Tree Fondant & Icing sugar from Amazon all the time as I have so many UK cookbooks. The Caster comes in 3-pound containers, and the Fondant comes in 2-pound containers. My issue is always with self-rising Flour, which is different from American self-raising flour. Sweet has a workaround on Page 353. Has anyone tried it? I don't get British self-rising flour because it so not easily available, and when I have found it, it (for instance at Myers of Keswick on Hudson Street, NYC), it has not had a long enough shelf life for me to spring for it. By the way, I use Lyle's Golden Syrup instead of corn syrup when I make Jeni's Sweet Cream Ice Cream. It is fantastic and gives it a rather elusive slightly caramel flavor.
Lindsay-Jean H. December 14, 2017
I love the golden syrup for corn syrup sub in Jeni's, I'm copying that!
Sandra R. December 14, 2017
I used the "make your own" approach for years, until I realized I had gone through 2 food processor bowls in 5 years. Factoring in the wear and tear on my food processor, I decided that buying "baker's sugar" was worth the price!
Mona P. December 14, 2017
Do you use a 1:1 ratio when substituting caster sugar for granulated? I would assume so for weight, but wouldn't 1:1 by volume result in more sugar with caster sugar than with the original granulated?
Lindsay-Jean H. December 14, 2017
Yes, you do. I know, it does seem like that would be the case, but from everything I've seen, both caster sugar and granulated sugar have the same 1 cup = 200 grams measurement.
Mona P. December 14, 2017
Hmm, I've seen caster sugar as weighing out to 225 g for a cup while granulated sugar is 200 g per cup. If that is actually true, and you substituted one cup of granulated sugar for the recipe recommended once cup of caster sugar, then the recipe would be shortchanged by 25 g of sugar. I wonder if that could be causing at least some of the changes in texture?
Lindsay-Jean H. December 14, 2017
Interesting, I'll ask Helen!
Lindsay-Jean H. December 14, 2017
I stand corrected! The response from Helen: "one cup of caster sugar here is 225g and granulated sugar comes in at 220g. I think it is less likely that the reduced quantity of sugar (if the conversion falls short) is what is affecting the texture. My hunch is that the granulated sugar perhaps does not dissolve as efficiently during creaming/beating etc. The texture as a result would be coarser or drier.”
Mona P. December 14, 2017
Ahh-- that makes sense! Thank you!
Maggie December 14, 2017
Can you use same amount of castor sugar if a recipe calls for granulated?
Lindsay-Jean H. December 14, 2017