Pearl sugar

One US cup of pearl sugar weighs 192 grams (6.8 ounces). Going the other way, 100 grams is about 0.52 cups.

Also called Swedish pearl sugar, pärlsocker, nib sugar, sugar nibs, hail sugar, decorating pearl sugar.

Sugars compared: cup weights side by side, the source behind each, and why they differ.

A cup of Swedish pearl sugar weighs 192 g (6.8 oz), a density of 0.81 g/mL, a little lighter than granulated sugar. King Arthur's own recipes weigh it at 96 g per half cup, the Lars Own label gives 8 g per 2 teaspoons, and King Arthur's chart, at 196 g, agrees within 2%. Belgian pearl sugar is a different product, with lumps several times larger, and weighs about 156 g per cup.

Pearl sugar is not crystallized like ordinary sugar. It is made by pressing sugar crystals into a hard mass, breaking it up and screening the pieces by size. Each piece is a cluster of small crystals with air between them, so it looks opaque white rather than clear, and it keeps its shape through baking, which is why it is scattered on Scandinavian cardamom buns, braided breads and cookies. Südzucker, a large European producer, sells pearl sugar in seven grades, from P1 at 1.25 to 2.5 mm up to P5 at 8 to 16 mm. Swedish pearl sugar (pärlsocker) is the small end, round nibs of about 2 mm. Belgian pearl sugar is the large end, irregular lumps that stay whole inside Liège waffles.

The sources here all describe the small Swedish nibs. King Arthur's Pumpkin Sugar Crunch Waffles recipe calls for 1/2 cup (96 g) of Swedish pearl sugar, 192 g per cup. The Lars Own label prints a serving of 2 teaspoons (8 g), 36 servings in a 10 oz bag. Sugar's FDA reference amount is 8 g, stated in teaspoons, so the label weighs a fixed 8 g and gives the nearest teaspoon count; it supports the figure but could not decide it alone. King Arthur's ingredient weight chart lists 1/4 cup at 1 3/4 oz, 49 g, which is 196 g per cup, within 2% of the other two and accepted.

The physical check: sucrose crystals have a density of 1.59 g/mL, and granulated sugar poured into a cup fills about 53% of it, 200 g on this site. A pearl-sugar nib is itself partly air, and round nibs of one size leave about as much space between them as fine crystals do, so pearl sugar should weigh slightly less than granulated sugar by volume. At 0.81 g/mL it does, and it sits with demerara sugar (192 g) and caster sugar (190 g) rather than with coarse turbinado.

Belgian pearl sugar behaves differently. America's Test Kitchen weighs 1 cup at 5 1/2 oz, 156 g, 0.66 g/mL, in its Liège waffle recipe, and warns against using the smaller Swedish kind there. Lumps that large cannot settle into the corners and against the walls of a cup, so far more of the cup is air. It is the only measured Belgian figure found, so this entry does not publish it as a figure of its own; one source is not enough.

Practical guidance: use 192 g per cup of Swedish pearl sugar, 48 g per quarter cup and 12 g per tablespoon. For Belgian pearl sugar use about 156 g per cup, and weigh it whenever a recipe gives grams, because the lump size varies from bag to bag. The two are not interchangeable: a Liège waffle needs lumps large enough to survive in the dough, and Belgian lumps are too large to stay on top of a bun.