castor sugar / sugar (equal parts

Castor sugar, also known as superfine sugar or caster sugar, is a granulated white sugar with crystals significantly smaller than standard granulated sugar. Produced by refining sugar cane or sugar beets and then grinding the crystals to a fine, uniform size, castor sugar measures approximately 0.5 mm in diameter. The finer crystal structure dissolves more readily in liquids and incorporates more uniformly into batters and doughs compared to coarser granulated sugar, making it a preferred choice in baking and beverage applications. It is chemically identical to granulated sugar (sucrose) but distinguished primarily by particle size.

The texture of castor sugar is noticeably finer and more powdery than standard granulated sugar, yet coarser and less dense than confectioners' (powdered) sugar. This intermediate size makes it particularly valued in professional and home baking across English-speaking countries, where it is the standard sugar for many recipes.

Castor sugar is essential in baking, where its fine crystals dissolve quickly and distribute evenly throughout batters, cakes, cookies, and meringues. It is particularly valued in meringue preparation, where its granule size allows for faster incorporation of air when whipped with egg whites, producing finer, more stable foam. Castor sugar is also preferred for sprinkling on finished baked goods, dusting desserts, and dissolving into cold beverages such as iced tea and cocktails. In British and Commonwealth cuisines, it is the standard sugar for Victoria sponge cakes, shortbread, and custard-based desserts. Its uniform particle size ensures consistent texture and appearance in finished products where standard granulated sugar might leave visible grains.