1 Cup Caster Sugar in Grams
1 cup of caster sugar weighs 190 g (spooned and levelled, King Arthur Baking). Fine-grained white sugar that dissolves faster than granulated sugar. All the figures on this page are approximate conversions based on the King Arthur Baking value, so when a recipe really matters, verify with a kitchen scale.
Caster sugar is granulated sugar ground to a finer crystal, and that small difference in crystal size changes how it behaves. It dissolves faster than granulated sugar, which makes it the sugar of choice for meringues, cocktails, shortbread and custards, where undissolved crystals would leave a gritty texture. A cup weighs 190 g, a little less than granulated sugar at 198 g, because the finer crystals pack slightly differently. In Britain it is the default sugar for baking, while in the United States it is a speciality item, which is why so many recipes that call for it confuse American bakers who have only ever bought granulated sugar.
Caster Sugar cups to grams conversion table
| Cups | Grams | Tablespoons |
|---|---|---|
| 1/4 cup | 47.5 g | 4 |
| 1/3 cup | 63.3 g | 5.3 |
| 1/2 cup | 95 g | 8 |
| 2/3 cup | 126.7 g | 10.7 |
| 3/4 cup | 142.5 g | 12 |
| 1 cup | 190 g | 16 |
| 1 1/2 cups | 285 g | 24 |
| 2 cups | 380 g | 32 |
| 3 cups | 570 g | 48 |
| 4 cups | 760 g | 64 |
One tablespoon of caster sugar weighs about 11.9 g, and a cup is 16 tablespoons, so the tablespoon column is simply the cup weight divided by 16. For small amounts, a scale that reads to the gram is far more reliable than a spoon, because a heaped tablespoon can weigh half as much again as a level one. All the values in this table are approximate, and they assume the ingredient is measured spooned and levelled, exactly as the source measured it.
Why a scale beats a cup for caster sugar
Sugar looks like the easiest ingredient to measure in cups, because the crystals pour cleanly and level neatly, but the weight per cup still varies a lot between types. A cup of granulated sugar weighs about 198 g, a cup of powdered sugar about 113 g, and a cup of packed brown sugar about 213 g, so swapping one sugar for another cup-for-cup changes the sweetness and the structure of a bake by a large margin. Sugar does more than sweeten: it holds moisture, tenderises crumb, feeds yeast, helps browning and sets the texture of everything from meringues to caramel. Getting the weight right is what keeps a cake moist instead of dry, a meringue crisp instead of weeping, and a jam setting instead of running. Because sugar dissolves, small errors are forgiving in drinks and sauces, but in baking they are not.
Worked examples
Meringues that need 1 cup
A batch of meringues that calls for 1 cup of caster sugar needs 190 g, beaten a spoonful at a time into whipped egg whites. The fine crystals dissolve quickly into the foam, which is what gives meringues their smooth, glossy finish instead of a gritty, weeping one. If you used granulated sugar instead, the crystals would take longer to dissolve and some would survive into the oven, where they melt and leave sticky spots on the finished meringue.
Shortbread for afternoon tea
A shortbread recipe that uses 1/2 cup of caster sugar needs 95 g, creamed with butter until pale and fluffy. The fine sugar creams more smoothly than granulated sugar and gives the shortbread a finer, more melting crumb. Weigh 95 g rather than measuring by volume, because a cup of caster sugar is lighter than a cup of granulated sugar, and a recipe that expects one and gets the other will be sweeter and denser than intended.
A sponge cake for a celebration
A sponge cake that calls for 3/4 cup of caster sugar needs 142.5 g. The sugar is beaten with the eggs until the mixture is thick and pale, and the fine crystals dissolve fully during the beating, which helps the sponge rise evenly. Granulated sugar can work in a sponge, but it needs longer beating to dissolve, and undissolved crystals weigh the batter down and leave a coarse crumb.
How the weight was measured
spooned and levelled means filling the cup with a spoon rather than plunging the cup into the bag or jar, then sweeping a straight knife across the top to level it off. Never scoop, and never tap the cup down, because both pack the ingredient and add weight. The difference between a spooned cup and a scooped cup can be 15 to 25 percent, which is enough to change a bake from tender to tough, so the method matters as much as the number. The source for the figure on this page is King Arthur Baking, and the confidence in the value is high. King Arthur Baking publishes a standard ingredient weight chart that recipe developers use as a reference, and this page follows that chart rather than any single cookbook. Where the chart gives a range or a note, we say so plainly instead of hiding the uncertainty. All the figures here are approximate conversions: natural ingredients vary by brand, variety, moisture and how finely they are chopped or ground, so when a recipe really matters, verify the weight with a kitchen scale.
Common mistakes
The most common mistake is treating all sugars as interchangeable by volume. A cup of powdered sugar is nearly half the weight of a cup of granulated sugar, so a recipe that expects one and gets the other will be badly under- or over-sweetened. The second mistake is packing brown sugar when the recipe expects it spooned, or the reverse: packed brown sugar weighs about 213 g per cup while loosely spooned brown sugar weighs around 170 g, a difference of more than 40 g. The third is measuring sticky syrups in a dry cup and losing half of it on the sides; a light wipe of oil on the cup helps a syrup slide out cleanly. And the fourth is sifting powdered sugar before measuring it, which adds air and drops the weight per cup to around 100 g. Measure first, then sift.
When this conversion matters most
This conversion matters most in baking and preserving, where sugar controls structure as well as sweetness. In cakes it tenderises the crumb and holds moisture; in meringues it stabilises the foam; in jams it sets the pectin and preserves the fruit. It matters less in a cup of tea or coffee, where a gram or two either way is a matter of taste and you can adjust by sipping. It matters again when you scale recipes, because sugar errors multiply just like flour errors, and a doubled batch of cookies with too much sugar spreads thin and burns at the edges. When a recipe was developed by weight, matching that weight is the simplest way to match the result.
What to do if you do not have a scale
If you do not have a scale, use a dry measuring cup and the method the figure on this page was measured with: spooned and levelled for free-flowing sugars, firmly packed for brown and muscovado sugars, and poured at eye level for syrups. For syrups, measure in a liquid jug at eye level and use a flexible spatula to scrape every last drop out. For powdered sugar, spoon it in lightly and level it, and do not press it down. These methods get you close, but sugar is cheap to weigh and expensive to get wrong in baking, so a scale is the better investment here than for almost any other ingredient.
Storing caster sugar
Airtight container, cool and dry, indefinitely. Keeping caster sugar properly stored matters for the conversion as well as for the flavour: an ingredient that has absorbed moisture from the air weighs more per cup than a dry one, and one that has dried out weighs less. Store it in an airtight container, away from heat and light, and measure it in the state the recipe expects, not straight from a damp or stale bag.
Frequently asked questions
What is the difference between caster sugar and granulated sugar?
Caster sugar is the same sugar ground to a finer crystal, so it dissolves faster and creams more smoothly. A cup of caster sugar weighs 190 g, while a cup of granulated sugar weighs 198 g, so they are not identical by volume. Use caster sugar for meringues, mousses, cocktails and delicate cakes, where a smooth texture matters, and granulated sugar for everyday sweetening and for recipes where the sugar is dissolved in liquid anyway.
Can I make caster sugar from granulated sugar?
Yes, by pulsing granulated sugar in a food processor or spice grinder for a few seconds at a time until the crystals are finer. Do not over-process it or it turns into powdered sugar, which is a different ingredient with a different weight per cup. Pulse, check, and stop as soon as the crystals look fine and even, then weigh the result at 190 g per cup.
Can I use cups instead of a scale for caster sugar?
Yes, but a scale is more accurate. If you measure caster sugar spooned and levelled, exactly as the figure on this page was measured, a cup will be close to 190 g, within a few grams. The problem is that most people scoop rather than spoon, which can add 15 to 25 percent to the weight, and that error is enough to change a bake. For everyday cooking, cups are fine. For baking, where the ratio of ingredients decides the result, weigh it and check the number on the scale.
How many tablespoons are in a cup of caster sugar?
There are 16 tablespoons in a US cup, so a cup of caster sugar is 16 tablespoons, and one tablespoon weighs about 11.9 g. A teaspoon weighs about 4 g. Tablespoons are useful when a recipe calls for a small amount, but they carry the same packing problem as cups: a heaped tablespoon can weigh half as much again as a level one, so level every spoon with the back of a knife, and use a scale for small amounts when accuracy matters.
Does the weight change if I pack or sift caster sugar?
Yes, and this is the single biggest source of error in cup measurements. caster sugar is measured spooned and levelled, and a scooped cup can weigh 15 to 25 percent more than a spooned cup, because scooping packs the ingredient down. Sifting has the opposite effect: it adds air and makes the cup lighter. Always measure the way the figure on this page was measured, spooned and levelled, and the weight will match the table.