Powdered Sugar (icing sugar): Grams to Cups

Sifted or not makes a 20% difference

Powdered sugar is ground so fine that it traps a lot of air when sifted and packs down in the bag when it is not. USDA measures 120 g for an unsifted cup and 100 g for a sifted one; King Arthur's unsifted figure is 113 g. For frosting that difference changes consistency noticeably.

Follow the recipe's wording: "1 cup sifted powdered sugar" is about 100 g; "1 cup powdered sugar, sifted" is measured first, so about 120 g.

Other names

Icing sugar (UK, Australia, Canada), confectioners' sugar and 10X sugar are the same product for measuring purposes. A 2 lb (907 g) bag holds about 7½ cups unsifted.

Using it in frosting and glaze

Buttercream typically runs about two parts powdered sugar to one part butter by weight — for example 454 g of powdered sugar (a 1 lb box, about 3¾ cups unsifted) to 227 g of butter. A simple glaze is roughly 120 g (1 cup) of powdered sugar to 2–3 tablespoons of milk or lemon juice. Because it dissolves instantly, powdered sugar is not a substitute for granulated sugar in cakes or cookies.

You can make it at home by blitzing granulated sugar in a blender until powdery, adding about 1 tablespoon of cornstarch per cup to prevent clumping. It will measure lighter by the cup than the sugar you started with.

Where the 120 g figure comes from

• USDA FoodData Central: 1 cup unsifted of “Sugars, powdered” = 120 g (FDC ID 169656)
• King Arthur Baking ingredient weight chart: Confectioners' sugar (unsifted), 1 cup = 113 g (chart)

This site uses 120 g per US cup of powdered sugar (icing sugar), spooned and levelled. References checked September 2026.

How many cups is X grams of powdered sugar (icing sugar)?

How to measure powdered sugar (icing sugar) accurately

The 120 g figure assumes the spooned-and-levelled method: spoon the powdered sugar (icing sugar) into a dry measuring cup and sweep the top flat with a straight edge. Scooping the cup through the bag compacts it and gives a heavier cup.

• 1 US cup of powdered sugar (icing sugar) = 120 g
• 1 metric cup (250 ml) of powdered sugar (icing sugar) = 127 g
• ¾ cup = 90 g
• ½ cup = 60 g
• ⅓ cup = 40 g
• ¼ cup = 30 g
• 1 tablespoon = 7.5 g

Frequently asked questions

How many cups is 100 grams of powdered sugar (icing sugar)?

100 grams of powdered sugar (icing sugar) is about ⅞ US cups, based on 120 g per cup, or ¾ metric cups.

How many grams in a cup of powdered sugar (icing sugar)?

One US cup of powdered sugar (icing sugar) weighs 120 grams. A 250 ml metric cup holds 127 grams.

How many cups is 250 grams of powdered sugar (icing sugar)?

250 grams of powdered sugar (icing sugar) is about 2⅛ US cups, or 2 metric cups.

Does a UK cup of powdered sugar (icing sugar) weigh the same as a US cup?

No. A UK, Australian or Canadian metric cup is 250 ml against the US 236.6 ml, so it holds about 5.7% more — 127 g of powdered sugar (icing sugar) rather than 120 g.

How many tablespoons is 100 grams of powdered sugar (icing sugar)?

100 grams of powdered sugar (icing sugar) is about 13.33 tablespoons.