Is Icing Sugar the Same as Powdered Sugar? A UK Guide
Is icing sugar the same as powdered sugar? Yes. Icing sugar (the UK name), powdered sugar and confectioners' sugar (the US names) are all white sugar milled to a fine powder. US packs usually add a little cornstarch to stop clumping. UK packs vary: some add maize starch, others tricalcium phosphate. Royal icing sugar is different, because it also contains dried egg white.
At a glance
- Same thingicing, powdered and confectioners' sugar
- 2–5%cornstarch in Domino US powdered sugar
- 97%cane sugar in Tate & Lyle icing sugar
- 104.9gcarbohydrate per 100g of icing sugar (CoFID)
On this page
American recipes ask for "powdered sugar" or "confectioners' sugar", and you won't find either name on a bag in most British supermarkets. The good news is that you already know the ingredient: it's icing sugar.
This guide explains how the UK and US names line up, what's actually in the bag on each side of the Atlantic, how royal and fondant icing sugar differ, and which powdered sweeteners to reach for if you're baking low-carb.
Is icing sugar the same as powdered sugar and confectioners' sugar?
All three names describe the same thing: ordinary white sugar ground into a very fine, soft powder. Silver Spoon's specification for its icing sugar gives an average particle size of about 19 to 26 microns, far finer than caster or granulated sugar. That's why it dissolves almost instantly into butter, cream cheese or a few drops of water, making smooth icings without any grittiness.
- Icing sugar is the usual name in the UK, Ireland, Australia and New Zealand.
- Powdered sugar is the everyday US name.
- Confectioners' sugar is another US name for the same product. American packs sometimes add a grade such as 10X, which simply tells you how finely it's milled.
So if a US recipe asks for a cup of powdered sugar, use UK icing sugar. Just weigh it if you can, because a fluffy powder packs down differently every time you scoop it. Our cups to grams conversion guide explains why weighing is more reliable.
UK and US sugar names compared
The confusion usually comes from the other "icing" sugars on the baking aisle, which aren't plain icing sugar at all.
| Name | Where | What's in it | Best for |
|---|---|---|---|
| Icing sugar | UK | Fine sugar, often with an anti-caking agent | Buttercream, glacé icing, dusting |
| Powdered sugar | US | Fine sugar plus cornstarch | Same as icing sugar |
| Confectioners' sugar | US | Fine sugar plus cornstarch | Same as icing sugar |
| Royal icing sugar | UK | Icing sugar plus dried egg white | Hard-set royal icing |
| Fondant icing sugar | UK | Icing sugar plus dried glucose syrup | Glossy soft-set icing |
| Caster sugar | UK | Fine-grained sugar, not powdered | Sponges, meringues |
Ingredients from Silver Spoon, Tate & Lyle and Domino packs and specifications, checked 25 October 2026. Caster sugar is sold as "superfine sugar" in the US.
Caster sugar is the one most often mixed up with icing sugar. Its crystals are smaller than granulated sugar, but they're still crystals, so it won't give you a smooth icing. Use it for creaming with butter in sponges, and keep icing sugar for anything that isn't baked.
What's in icing sugar? UK and US packs
Very fine sugar soaks up moisture from the air and sets into lumps, so most brands add a small amount of something to keep it free-flowing. What they add depends on the brand rather than the country name:
- Silver Spoon icing sugar (UK, made from sugar beet) lists icing sugar and an anti-caking agent, tricalcium phosphate (E341). Its specification puts this at 0.5% to 1%.
- Tate & Lyle icing sugar (UK, made from cane sugar) lists cane sugar (97%) and maize starch. Maize starch is what we call cornflour in the UK.
- Domino confectioners' sugar (US) lists sugar and cornstarch. Domino's specification allows 2% to 5% cornstarch.
- Silver Spoon royal icing sugar lists icing sugar, dried egg white and tricalcium phosphate. The egg white is what makes royal icing set hard.
- Silver Spoon fondant icing sugar lists icing sugar and dried glucose syrup, which gives a glossy, softer finish when you add water.
In practice, plain icing sugar and US powdered sugar behave the same in buttercream, glazes and dusting. The small amount of starch or anti-caking agent makes no noticeable difference in a recipe. If you're curious about the starch itself, our guide to whether cornflour is the same as cornstarch explains the naming.
Royal icing sugar contains egg, so don't use it in place of plain icing sugar for anyone with an egg allergy. Silver Spoon's plain and fondant icing sugars also carry a "may contain egg" warning, because they're made on a site that handles egg. Always check the pack.
Carbs in icing sugar
Icing sugar is almost pure sugar, so it's almost pure carbohydrate. These are the UK government's CoFID figures alongside the labels on two UK packs:
| Source | Carbs per 100g | Sugars per 100g | Energy |
|---|---|---|---|
| CoFID icing sugar | 104.9g | 103.8g | 393 kcal |
| Silver Spoon label | 100g | 100g | 400 kcal |
| Tate & Lyle label | 100g | 97g | 400 kcal |
Source: CoFID 2021, food code 17-062 (sugar, icing), and pack labels via Sainsbury's and Waitrose, checked 25 October 2026. Carbohydrate excludes fibre, as on UK labels; icing sugar contains none. CoFID gives more than 100g because it expresses carbohydrate as monosaccharide equivalents: sucrose gains weight on paper when it's counted as the glucose and fructose it splits into. Labels round to 100g.
Using the CoFID figure, 10g of icing sugar (a light dusting over a cake) contains 104.9 × 10 ÷ 100 = 10.5g of carbohydrate, and a 30g portion, the serving size on the Domino label, contains 104.9 × 30 ÷ 100 = 31.5g. A batch of buttercream made with 250g of icing sugar adds about 262g of carbohydrate (104.9 × 250 ÷ 100), nearly all of it sugars.
Powdered sweeteners with no added sugar
If you're baking low-carb, the job icing sugar does in a recipe still needs doing: a powder fine enough to melt into butter or cream without leaving grit. That's where a powdered sweetener comes in. We make two:
- Powdered Erythritol & Stevia Blend: sweetened with erythritol and stevia, with no added sugar. The ingredients are erythritol and stevia glycosides, and the label lists 0g of sugars, with all of its carbohydrate coming from polyols (erythritol).
- Powdered Monk Fruit and Erythritol Sweetener: sweetened with erythritol and monk fruit, with no added sugar. Its label also lists 0g of sugars, with its carbohydrate coming from polyols.
Both are finely powdered, so they suit buttercream, cream cheese frosting, whipped cream and dusting. Sift them before use, because powdered sweeteners can clump in the bag, and check the pack for how much to use. For a step-by-step look at how they behave in buttercream, glacé icing and royal icing, see our guide to icing sugar alternatives. Our keto cream cheese icing is a good first recipe to try, and a light dusting finishes our keto shortbread nicely.
Erythritol can recrystallise as it dries, so a glaze made with a powdered sweetener may set with a slightly frosted look rather than a glossy one. Dust bakes only once they're completely cold, or the powder soaks in and disappears.
Free delivery is on orders over £30.
Can you make icing sugar at home?
Yes. If a recipe calls for icing sugar and you only have caster or granulated sugar, you can grind your own:
- Make sure your blender jug, spice grinder or coffee grinder is completely dry. Any moisture makes the powder clump.
- Add the sugar in small batches, around 100g to 200g at a time, so it grinds evenly.
- Blitz in short bursts until it looks like flour, then leave it for a minute so the fine dust settles before you open the lid.
- Sift it, and store any you don't use in an airtight jar.
Home-ground sugar is rarely as fine as a commercial icing sugar, so buttercream may feel very slightly grainy. It's fine for dusting and most frostings. The same method works with a granulated sweetener such as our Granulated Erythritol & Stevia Blend if you've run out of a powdered one. Skip the cornflour some online tips suggest adding, because a quick re-blitz breaks up any lumps just as well.
Frequently asked questions
Can I use icing sugar instead of powdered sugar?
Yes. They are the same ingredient under different names, so use UK icing sugar wherever a US recipe asks for powdered or confectioners' sugar, at the same weight. US recipes often measure it in cups, so weigh it if you can, because a fluffy powder packs down differently every time you scoop it.
What is confectioners' sugar in the UK?
Confectioners' sugar is the American name for icing sugar: white sugar milled to a very fine powder, usually with a little cornstarch to stop it clumping. In the UK, buy ordinary icing sugar. Avoid royal icing sugar, which also contains dried egg white, and fondant icing sugar, which contains dried glucose syrup.
Does icing sugar contain cornflour?
Some does. Tate & Lyle icing sugar lists cane sugar (97%) and maize starch, which is cornflour. Silver Spoon icing sugar uses tricalcium phosphate as its anti-caking agent instead. US powdered sugar usually contains cornstarch, and Domino's specification allows 2% to 5%. Check the ingredients list on the pack you buy.
Can I make icing sugar from caster sugar?
Yes. Blitz caster or granulated sugar in a completely dry blender or spice grinder, in short bursts, until it looks like flour. Let the dust settle before opening the lid, then sift it. Home-ground sugar is rarely as fine as shop-bought, so buttercream may feel slightly grainy. Store any leftovers in an airtight jar.
What can I use instead of icing sugar with no added sugar?
A powdered sweetener is the closest match. Our Powdered Erythritol & Stevia Blend and Powdered Monk Fruit and Erythritol Sweetener are both finely powdered for icing, frosting and dusting, with no added sugar. Our guide to icing sugar alternatives explains how each one behaves in buttercream, glacé icing and royal icing.
Sources
- Public Health England. Composition of foods integrated dataset (CoFID) 2021: food code 17-062 (sugar, icing). Per-portion figures are our own calculations.
- Pack labels and specifications, checked 25 October 2026: Silver Spoon Icing Sugar (Sainsbury's), Silver Spoon icing sugar product specification, Tate & Lyle Fairtrade Icing Sugar (Waitrose), Silver Spoon Royal Icing Sugar (Tesco) and Silver Spoon Fondant Icing Sugar (Open Food Facts).
- Domino Foods. Confectioners 10X product specification and confectioners sugar label.
- Silver Spoon. What is the difference between icing sugars?
- Groovy Keto product pages: Powdered Erythritol & Stevia Blend, Powdered Monk Fruit and Erythritol Sweetener and Granulated Erythritol & Stevia Blend: ingredients, nutrition labels and pack sizes.
