Powdered sugar substitutes: fineness matters

Ground granulated sugar is a possible fallback

King Arthur describes blending 198 g granulated sugar with a tablespoon of cornstarch until fine as a homemade confectioners’ sugar substitute. For a batter or dough, use the finished replacement by weight as the source advises. Grinding does not make a cup of granulated sugar equivalent to a cup of powdered sugar.

Choose according to the finish you need

A dusting, a smooth glaze, and a buttercream expose graininess differently. Inspect the ground sugar’s fineness before committing an entire frosting batch. Commercial powdered sugar is a more predictable choice when the finish must be especially smooth.

Powdered sugar is also called confectioners’ or icing sugar. It is not the same product as superfine or caster sugar, which retains small crystals rather than becoming a fine powder.

Before substituting

Read whether the recipe measures before or after sifting. If it gives grams, keep that quantity rather than introducing another volume conversion. Check the ingredient list of any commercial alternative, especially if avoiding a particular starch.

If the frosting is already grainy

Adding more liquid is not a universal cure. First establish whether the texture comes from the sugar, cold fat, or another ingredient. A frosting that has become too loose creates a second problem.

For a critical decorative finish, use the specified product or an icing recipe developed for granulated sugar and its required cooking method. Do not simply exchange the sugars inside an unrelated frosting formula.