Caster sugar is the British term for a fine sugar, named so because the granules are tiny enough to be sprinkled through a condiment dispenser known as a “caster.” In the United States, this sugar is called superfine.

The Facts

  • Caster sugar has such a fine grain that it dissolves almost instantly.
  • It’s made by pulverizing granulated sugar into finer grains.
  • It has a slightly thicker texture than confectioner’s sugar, but it’s finer than table sugar.
  • Caster sugar can be purchased refined or unrefined.

When to Use It

Caster sugar quickly liquefies when added to beverages—a particularly useful quality for sweetening cold drinks such as iced tea. If a cocktail calls for sugar, bartenders often use caster sugar because it won’t ruin the drink by leaving a syrupy layer behind.

Since caster sugar is so light, it’s ideal for making fluffy, whipped desserts such as meringues, mousses, and soufflés as well as sorbets, custards, cakes, and cookies. It can also be sprinkled on fruit.

Where to Find It

Authentic caster sugar or superfine sugar can be purchased in specialty food stores and online. If you don’t have it on hand for a recipe, make your own by pulverizing regular granulated sugar in a food processor for about a minute, or until it becomes powdery.

Caster or Castor

Caster sugar is also sometimes called “castor” sugar. Which is the correct spelling? Both. The latter used to be the common spelling, but the former is used more often now by some sugar manufacturers.


Do not use regular granulated or powdered (confectioner’s) sugar to replace caster sugar. Granulated sugar is too thick and will change the consistency of a mixture. Powdered sugar contains small amounts of cornstarch to keep it from clumping. This added cornstarch could potentially alter a recipe that calls for caster sugar.


Cook UK