Out of Caster sugar, one case
Caster sugar vs icing sugar
5 options, ranked, with the exact amount
Use Caster sugar → icing sugar
Same amount by weight as the caster sugar
Caster sugar and icing sugar are different: caster sugar has fine grains while icing sugar is a powder that usually contains a little anti-caking agent. They are equally sweet by weight but not by cup, and they do not swap in every recipe: icing sugar is a poor stand-in for caster sugar in meringues and creamed sponges, and caster sugar stays gritty in icings. For caster sugar, use superfine sugar. For icing sugar, use powdered sugar.
- Verdict —
- Tweak it
- What changes —
- similar taste, different texture
- Best for —
- shortbread and other short biscuits
One casethe full caster sugar card
Every option, one card
Ranked| # | Substitute | Instead of caster sugar | Verdict |
|---|---|---|---|
| 1 | Caster sugar → icing sugarshortbread and other short biscuits | Same amount by weightTweak it | Tweak it |
| 2 | Icing sugar → caster sugarbatters and doughs | Same amount by weightTweak it | Tweak it |
| 3 | Superfine sugarbaking | Same amountWorks | Works |
| 4 | Powdered sugarany recipe that calls for icing sugar | Same amount by weightTweak it | Tweak it |
| 5 | Granulated sugarbaking | Same amountTweak it | Tweak it |
Caster sugar → icing sugar
similar taste, different texture
Icing sugar is as sweet as caster sugar weight for weight, but it is a powder that usually contains a little anti-caking agent. It stands in for caster sugar only where the sugar just has to dissolve.
- Best for
- shortbread and other short biscuits, sweetening whipped cream, uncooked fillings and no-bake desserts
Swap by weight, not by cup: a cup of icing sugar weighs a little over half as much as a cup of caster sugar, so the same cupful makes the recipe much less sweet. Do not use it for meringues, pavlova or sponges that start by creaming butter and sugar, where the crystals matter.
Icing sugar → caster sugar
similar taste, different texture
Caster sugar is as sweet as icing sugar weight for weight, but its crystals only disappear where there is enough liquid or heat to dissolve them.
- Best for
- batters and doughs, cooked syrups and sauces, when you can blend it to a powder first
Swap by weight, not by cup. In buttercream, glace icing, royal icing or for dusting, caster sugar stays gritty: blend it to a fine powder in a blender or spice grinder first.
Superfine sugar
identical taste and texture
Superfine sugar provides identical sweetness and texture to caster sugar. Good for when you want the exact same functionality with fine-grained sugar.
- Best for
- baking, when you want identical results, fine texture, most sugar recipes
Use in equal amounts by volume. Superfine sugar has identical sweetness and texture to caster sugar. Ideal for all applications where fine sugar is needed.
Powdered sugar
similar taste, different texture
Powdered sugar is the US name for icing sugar, so the two replace each other measure for measure. In place of caster sugar it behaves exactly as icing sugar does.
- Best for
- any recipe that calls for icing sugar, frosting and glazes, dusting
For icing sugar, use the same amount. For caster sugar, swap by weight and keep it out of meringues and creamed sponges, as with icing sugar.
Granulated sugar
similar taste, different texture
Granulated sugar is the same sugar as caster sugar in larger crystals. It replaces caster sugar in most baking, and replaces icing sugar only once it is blended to a powder.
- Best for
- baking, when you want coarser texture, general use, most sugar recipes
For caster sugar, use the same amount; for meringues and fine sponges, pulse it in a blender or food processor for 30 to 60 seconds first. For icing sugar, blend it to a fine powder first or it stays gritty.
How it behaves in this recipe
Caster sugar and icing sugar are equally sweet by weight but behave differently. Caster sugar has fine grains that beat air into butter and dissolve steadily into egg whites; icing sugar is a powder that dissolves at once and usually carries a little anti-caking agent. That is why each swap here works only in some recipes, and why they are measured by weight.
Tips for substituting caster sugar
8 tips- Swap caster sugar and icing sugar by weight, not by cup: a cup of icing sugar weighs a little over half as much as a cup of caster sugar
- Icing sugar usually contains a small amount of anti-caking agent, often cornflour (cornstarch), which caster sugar does not
- Whip meringues and pavlova with caster sugar; some recipes fold icing sugar in afterwards, but it does not replace the caster sugar
- For a sponge that starts by creaming butter and sugar, keep caster sugar: the crystals beat air into the butter and a powder cannot
- For buttercream, glace icing, royal icing and dusting, keep icing sugar: caster sugar stays gritty because there is too little liquid to dissolve it
- No icing sugar? Blend caster or granulated sugar to a fine powder in a blender or spice grinder, and let the dust settle before opening the lid
- No caster sugar? Pulse granulated sugar in a blender or food processor for 30 to 60 seconds until fine but not powdery
- Shortbread written for icing sugar comes out crisper and less melting when made with caster sugar
Notes on caster sugar
- For caster sugar: Use superfine sugar for identical results
- For icing sugar: Use powdered sugar for identical results
- For both: Use granulated sugar, pulsed fine for caster sugar or blended to a powder for icing sugar
- For caster sugar: Use icing sugar by weight, but not in meringues or creamed sponges
- For icing sugar: Use caster sugar only where it will dissolve, or blend it to a powder first
Questions
5 questionsCan I substitute caster sugar with icing sugar?
Sometimes. Icing sugar can replace caster sugar by weight in shortbread, whipped cream and uncooked fillings. It is a poor swap in meringues, pavlova and sponges that cream butter with sugar, because it has no crystals and usually contains a little anti-caking agent. Measure by weight: a cup of icing sugar weighs a little over half as much as a cup of caster sugar.
What's the difference between caster sugar and icing sugar?
Caster sugar has fine grains while icing sugar is powdered. Both have similar sweetness but different textures. Caster sugar dissolves faster than granulated sugar but slower than icing sugar. Icing sugar also usually contains a small amount of anti-caking agent, often cornflour (cornstarch).
Can I use icing sugar instead of caster sugar?
Only in some recipes, and by weight rather than by cup. It works where the sugar just dissolves, such as shortbread, whipped cream and no-bake fillings. For meringues and creamed cakes, pulse granulated sugar in a blender instead.
What can I use instead of caster sugar or icing sugar?
For alternatives, use superfine sugar for caster sugar and powdered sugar for icing sugar. Granulated sugar replaces caster sugar as it is, and replaces icing sugar once it is blended to a powder.
Can I substitute powdered sugar for caster sugar?
Powdered sugar is the same product as icing sugar, so the same limits apply: swap by weight, and only where the sugar just dissolves. It is a poor swap in meringues and creamed sponges.