One cup of powdered sugar weighs 113 g, spooned and levelled, according to King Arthur Baking. Powdered sugar — also called icing sugar or confectioners' sugar — is granulated sugar ground to a fine powder with a little cornstarch to stop it clumping. It is the lightest sugar by volume, because the fine powder traps a lot of air, and that lightness is why a cup of powdered sugar weighs barely more than half a cup of granulated sugar. The figure matters for frostings, glazes and dusting, where powdered sugar is measured by the cup and the weight decides the texture. All weights on this page are approximate; sifted powdered sugar weighs about 100 g per cup because sifting adds air, so verify with a scale when precision matters.
Powdered Sugar: weight and measurement table
The table below gives the weight of powdered sugar in every measure you will use, from a teaspoon up to 2 cups, all derived from the King Arthur Baking figure of 113 g per cup, spooned and levelled. Every figure is approximate — spooned and levelled is a technique, not a machine setting — so when the recipe matters, weigh the ingredient on a kitchen scale instead.
| Amount | Weight (approx.) |
| --- | --- |
| 1 teaspoon | 2.4 g |
| 1 tablespoon | 7.1 g |
| 1/4 cup (4 tbsp) | 28.2 g |
| 1/3 cup | 37.7 g |
| 1/2 cup (8 tbsp) | 56.5 g |
| 3/4 cup (12 tbsp) | 84.8 g |
| 1 cup (16 tbsp) | 113 g |
| 2 cups | 226 g |
| 100 g | 0.9 cups |
There are 3 teaspoons in a tablespoon and 16 tablespoons in a cup, so you can move between any of these measures by multiplying or dividing. If a recipe calls for 100 g and you only have measuring cups, that is about 0.9 cups. Keep the cups to grams converter open while you cook and you will never need to do the arithmetic in your head.
What is Powdered Sugar?
Powdered sugar is granulated sugar ground to a fine powder with a little cornstarch. The cornstarch, usually about 3 percent, absorbs moisture and stops the fine powder from clumping into hard lumps. It is used for icings, glazes, dusting and buttercream, and it behaves differently from granulated sugar in one important way: it dissolves instantly, with no heat and no stirring, because its particles are so small. That is why it is the sugar for frostings and glazes — it gives a smooth, lump-free finish that granulated sugar cannot. It is also the sugar for dusting, because it sits on the surface of a cake or a doughnut as a fine white veil instead of crunching under the teeth. It keeps indefinitely in an airtight container in a cool, dry place, but it absorbs moisture and odours easily, so keep it sealed.
How to measure Powdered Sugar correctly
Powdered Sugar is measured spooned and levelled, and the method matters more than most cooks realise. For dry ingredients, spoon the ingredient into the measure with a smaller spoon, letting it fall loosely, then sweep a knife across the top to level it — never dip the measuring cup into the bag, because dipping compresses the ingredient and adds up to 20 percent. For liquids, pour into a liquid measuring jug and read the level at eye height, or weigh directly into the bowl, which is the most accurate method of all. The King Arthur Baking figure used on this page is 113 g per cup, and it is the figure the site's converters use, so the numbers here and the numbers in the tool always agree. Confidence in this figure is high.
A note on the published figures
King Arthur lists 113 g unsifted; sifted powdered sugar is about 100 g per cup because sifting adds air.
Worked examples
A buttercream for a birthday cake
A buttercream for a two-layer cake uses 4 cups of powdered sugar — about 452 g — beaten with 227 g of butter and a splash of milk. The weight matters because frosting is a ratio: 452 g of sugar to 227 g of butter is a 2:1 ratio that gives a frosting firm enough to hold its shape but soft enough to spread. Weighing the sugar keeps the ratio exact — a cup too much and the frosting is stiff and gritty, a cup too little and it slides off the cake. The sugar is sifted before beating, which removes lumps and gives a silky finish, and the milk is added a tablespoon at a time until the frosting reaches the right consistency.
A glaze for cinnamon rolls
A glaze for a tray of cinnamon rolls uses 1 cup of powdered sugar — 113 g — whisked with 2 tablespoons of milk and a teaspoon of vanilla. The weight is useful because the glaze's thickness depends on it: 113 g of sugar to 30 g of milk gives a glaze that pours in a ribbon and sets into a thin, white coating. A glaze made with too much sugar is thick and opaque, while too little sugar gives a watery wash that disappears into the rolls. The glaze is poured over the rolls while they are still warm, so it melts slightly and seeps into the swirls.
Dusting a chocolate cake
A chocolate cake is finished with 2 tablespoons of powdered sugar — about 14 g — dusted over the top through a fine sieve. The weight matters because dusting is about restraint: 14 g is enough to give the cake a delicate white veil, while a tablespoon more leaves a thick, chalky layer that tastes of raw sugar. The sugar is sifted from a height of about 30 cm, which distributes it evenly, and it is done just before serving, because the sugar absorbs moisture from the cake and disappears within an hour. For a cake that will sit for a while, a dusting of cocoa powder lasts longer than powdered sugar.
Sifting and clumping
Powdered sugar's defining problem is clumping. The powder is so fine that it absorbs moisture from the air and forms hard lumps, and those lumps do not dissolve in a frosting — they stay as gritty white specks that ruin the texture. That is why every frosting recipe says to sift the powdered sugar, and why the weight changes when you do: unsifted powdered sugar weighs 113 g per cup, while sifted powdered sugar weighs about 100 g per cup, because sifting adds air. The difference is not trivial — across 4 cups of sugar for a buttercream, it is 52 g, which changes the frosting's stiffness noticeably. The practical rule is to weigh the sugar before sifting, or to sift it and then weigh it, but not to do both at different times and expect the same result. For dusting, sifting is essential: unsifted sugar leaves clumps on the cake, while sifted sugar falls as a fine, even veil. And for storage, keep powdered sugar in an airtight container with a tight lid — it absorbs odours as readily as moisture, and a bag stored next to the spices will taste of cinnamon within a week.
What to use instead
If you run out of powdered sugar, these are the tested substitutes from our substitution data, with the ratio and the case where each one does not work. Use the ratio by weight where it is given, and check the warning before you commit the batter.
- Powdered sugar to Granulated sugar: 1 cup granulated sugar per 1 3/4 cups powdered sugar. Do not swap 1:1 in candy-making, meringues or jam, where sugar's exact chemistry matters.
The golden rule for any substitution is to match the job, not just the ingredient: a substitute that works in a sauce may fail in a cake, because the two recipes ask different things of the ingredient. When in doubt, use a recipe written for the substitute rather than adapting one written for the original.
Storage
Airtight container, cool and dry, indefinitely. That is the headline, but the details matter. Store powdered sugar in an airtight container, away from heat, light and strong smells — dry ingredients absorb odours readily, and a bag of flour stored next to the spices will taste of them within a week. Label the container with the date you opened it, so you know how long it has been there, and check it before you bake: if it smells off, tastes bitter, or shows any sign of moisture or insects, discard it. Buying in smaller quantities and using it promptly is better than buying in bulk and storing it for a year, because every ingredient loses flavour with time, even the ones that never truly go bad.
Frequently asked questions
How many grams is 1 cup of powdered sugar?
One cup of powdered sugar weighs 113 g, spooned and levelled, according to King Arthur Baking. Sifted powdered sugar weighs about 100 g per cup, because sifting adds air. One tablespoon weighs 7.1 g.
How many cups of powdered sugar are in 500 g?
There are about 4.4 cups in 500 g of unsifted powdered sugar (500 divided by 113 is 4.4 cups). A standard 500 g bag holds just over 4 cups.
Can I use granulated sugar instead of powdered sugar?
Not directly. Granulated sugar does not dissolve the same way and gives a gritty frosting. You can make powdered sugar by blending granulated sugar in a high-speed blender until fine, then adding a teaspoon of cornstarch per cup to stop clumping. For a glaze, use 1 3/4 cups of powdered sugar per cup of granulated sugar.
Why is my frosting lumpy?
Usually unsifted powdered sugar. The fine powder clumps with moisture, and the lumps do not dissolve when beaten. Sift the sugar before adding it, and beat the butter alone first until smooth, then add the sugar gradually.
How long does powdered sugar last?
Indefinitely, in an airtight container in a cool, dry place. It absorbs moisture and odours easily, so keep it sealed and away from strong smells. Discard it if it has hardened into a solid block that will not break up, or if it smells of anything other than sugar.
Related pages
If you cook with this ingredient regularly, these pages will help: the cups to grams converter for any amount, the ingredient density lookup for the full table of 120 ingredients, the Powdered Sugar cups to grams page for cup conversions, the Powdered Sugar grams to cups page for working backwards from grams, and the Powdered Sugar tablespoons to grams page for spoon measures. You may also want Granulated Sugar, Brown Sugar.