Cups of Powdered Sugar to Grams (Sifted vs Unsifted)
1 cup of unsifted powdered sugar weighs 113 g (King Arthur Baking: "Confectioners' sugar (unsifted): 1 cup = 113 g"). Sift it first and a cup drops to about 100 g on the USDA chart. Frosting recipes live or die on which of those two cups the author meant.
Source: Confectioners' sugar (unsifted): 1 cup = 113 g (King Arthur Baking, Ingredient Weight Chart). Unsifted. USDA lists 120 g unsifted and 100 g sifted (fdcId 169656).
| Cups | Grams (US cup) | Ounces (US cup) | Grams (metric cup, 250 ml) |
|---|---|---|---|
| 1/8 cup | 14 | 0.498 | 15 |
| 1/4 cup | 28 | 0.996 | 30 |
| 1/3 cup | 38 | 1.33 | 40 |
| 1/2 cup | 56 | 1.99 | 60 |
| 2/3 cup | 75 | 2.66 | 80 |
| 3/4 cup | 85 | 2.99 | 90 |
| 1 cup | 113 | 3.99 | 119 |
| 1 1/2 cups | 170 | 5.98 | 179 |
| 2 cups | 226 | 7.97 | 239 |
| 3 cups | 339 | 11.96 | 358 |
| 4 cups | 452 | 15.94 | 478 |
| Grams | US cups | Measuring-cup version |
|---|---|---|
| 25 g | 0.221 | about 3 tbsp + 1 ½ tsp |
| 50 g | 0.442 | about ⅓ cup + 1 tbsp + 2 tsp |
| 100 g | 0.885 | about ¾ cup + 2 tbsp |
| 125 g | 1.11 | about 1 cup + 1 tbsp + 2 tsp |
| 150 g | 1.33 | about 1 ¼ cups + 1 tbsp + 1 tsp |
| 200 g | 1.77 | 1 ¾ cups + 1 tsp |
| 250 g | 2.21 | about 2 cups + 3 tbsp + 1 tsp |
| 300 g | 2.65 | about 2 ½ cups + 2 tbsp + 1 tsp |
| 400 g | 3.54 | about 3 ½ cups + 2 tsp |
| 500 g | 4.42 | about 4 ⅓ cups + 1 tbsp + 1 tsp |
| 1,000 g | 8.85 | about 8 ¾ cups + 1 tbsp + 2 tsp |
| Measure | Grams | Milliliters |
|---|---|---|
| 1/4 tsp | 0.6 | 1.23 |
| 1/2 tsp | 1.2 | 2.46 |
| 1 tsp | 2.4 | 4.93 |
| 1 tbsp (3 tsp) | 7.1 | 14.79 |
| 2 tbsp (1/8 cup) | 14.1 | 29.57 |
| 4 tbsp (1/4 cup) | 28.2 | 59.15 |
| 8 tbsp (1/2 cup) | 56.5 | 118.3 |
Worked example: a buttercream that needs 3 cups of powdered sugar
- Take the recipe at face value, unsifted: 3 × 113 g = 339 g.
- If it meant sifted first, use the USDA sifted cup: 3 × 100 g = 300 g.
- Compare them: 339 g − 300 g = 39 g.
- Start with the lower weight, taste, then add sugar a spoonful (7.06 g) at a time until the frosting holds its shape.
Three numbers for one sugar
Powdered sugar (also called confectioners' or icing sugar) packs unpredictably because it is a very fine powder with a little cornstarch in it. The published figures are:
- King Arthur Baking, unsifted: 113 g per cup
- USDA FoodData Central, unsifted: 120 g per cup
- USDA FoodData Central, sifted: 100 g per cup
The spread from sifted to USDA-unsifted is 20 g, which is 20% heavier. The site uses the King Arthur Baking value of 113 g as its default.
"1 cup, sifted" versus "1 cup sifted"
Recipe punctuation changes what you do. "1 cup powdered sugar, sifted" means measure first, then sift, so you use an unsifted cup. "1 cup sifted powdered sugar" means sift first, then measure, which leaves you with fewer grams.
In weights, the first reading is 113 g and the second, using USDA, is 100 g. For a 3-cup frosting that is 339 g against 300 g, a gap of 39 g, and the thicker version may need extra liquid.
Frosting and glaze tips
- Sift to remove lumps even when the recipe does not say so; just weigh afterwards.
- Add liquid a teaspoon at a time, since a loosely measured cup may need more than the recipe lists.
- Don't swap powdered sugar for granulated by cup. A cup of granulated is 198 g, about 1.75 times the weight.
Scooping, spooning or weighing
Never scoop powdered sugar straight from the bag: it compresses and you add grams you did not plan for. Spoon it lightly into the cup, or weigh it, which is best because powdered sugar is bulky and inconsistent. One tablespoon is 7.06 g, handy for dusting amounts.
Why it clumps and what to do
Powdered sugar contains a little starch to stop clumping, but it still absorbs moisture from the air. Store it airtight, break up hard lumps with a fork, and weigh it after sifting if the recipe gives grams. A cup full of loose lumps and air pockets weighs less than a smooth, settled one.
Dusting and decorating amounts
A quarter cup of unsifted powdered sugar is 28.3 g and two tablespoons is 14.1 g. That is plenty to dust a cake or a batch of doughnuts. When a recipe says "dust generously", you will often use a half cup, which is 56.5 g.
Metric cup, same ingredient
In a 250 ml cup the figure is about 119 g (0.4776 g per ml × 250 ml). Icing sugar in Australian recipes is typically listed in cups or grams, so check which your method uses before you convert.
Frequently asked questions
How many grams are in 1 cup of powdered sugar?
1 US cup of unsifted powdered sugar is 113 g (King Arthur Baking). USDA lists 120 g unsifted and 100 g sifted.
Is icing sugar the same as powdered sugar?
Icing sugar is the British and Australian name for powdered or confectioners' sugar, so the same cup weights apply.
How many grams are in half a cup of powdered sugar?
Half a cup unsifted is 56.5 g, and a quarter cup is 28.3 g.
Does sifting change the weight?
Sifting first and then measuring gives a lighter cup of about 100 g; measuring first and then sifting does not change the weight.
Can I use granulated sugar instead?
Not for frosting. Granulated sugar will not dissolve into a smooth finish, and it weighs more per cup.