Icing Sugar — Cups to Grams
1 cup of icing sugar = 120 grams
1 cup of icing sugar weighs approximately 120 grams. Use the converter below for custom amounts, or check the full conversion table.
Icing Sugar Converter
Result
120 g
Why Does Icing Sugar Weigh 120g Per Cup?
Icing sugar has the same density as flour — about half that of water. The ultra-fine particles create significant air space, and the added cornstarch (about 3%) makes it even lighter. This powdery texture means icing sugar compacts dramatically when scooped or packed, making volume measurements unreliable without sifting first.
A cup of icing sugar (120g) weighs the same as a cup of flour, but only 60% as much as a cup of granulated sugar (200g). Despite being made from the same substance, the grinding process creates a completely different density.
When Does Precision Matter for Icing Sugar?
Icing sugar precision matters most in royal icing, where the sugar-to-liquid ratio determines consistency for piping vs flooding. In buttercream, being off by 10-20% affects sweetness but not structure. For glazes, adjust to desired thickness. When dusting baked goods, precision doesn't matter at all. The biggest variable is whether you sift before or after measuring — unsifted icing sugar can weigh 30% more per cup due to compaction.
How to Measure Icing Sugar Correctly
Icing sugar should be sifted before measuring to break up any lumps, then spooned into the measuring cup and levelled off. Never scoop it directly from the container, as this can compact it significantly. For the most accurate measurements, especially in delicate recipes like buttercream, use a kitchen scale.
Understanding Icing Sugar Measurements
Icing sugar (also called powdered sugar or confectioners' sugar) is finely ground sugar mixed with a small amount of cornstarch to prevent clumping. One cup of icing sugar weighs approximately 120 grams. Its fine, powdery texture means it can be easily compacted if not measured carefully.
Common Uses in Baking & Cooking
Icing sugar is used primarily for making frostings, glazes, and dusting baked goods. It dissolves quickly, making it ideal for icings and buttercreams. It's also used to make royal icing and decorative piping. The fine texture means it creates smooth, lump-free frostings. If you need a substitute, see our Icing Sugar substitution guide.
Storage and Handling Tips
Store icing sugar in an airtight container in a cool, dry place. It has a long shelf life but can clump if exposed to moisture. If it becomes clumpy, sift it before using. The cornstarch in icing sugar helps prevent clumping but can affect some recipes if you need pure sugar.
Need to convert icing sugar to other units? Try our cups to grams converter or tablespoons to grams converter.
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Icing Sugar Conversion Table
| Amount | Grams | Ounces |
|---|---|---|
| 1 teaspoon | 2.5g | 0.09 oz |
| 1 tablespoon | 7.5g | 0.26 oz |
| ¼ cup | 30g | 1.06 oz |
| ⅓ cup | 40g | 1.41 oz |
| ½ cup | 60g | 2.12 oz |
| ⅔ cup | 80g | 2.82 oz |
| ¾ cup | 90g | 3.17 oz |
| 1 cup | 120g | 4.23 oz |
| 1½ cups | 180g | 6.35 oz |
| 2 cups | 240g | 8.47 oz |
Icing Sugar — US, Metric & UK Cup Conversions
Cup sizes vary by country. This table shows how much icing sugar weighs when measured with US cups (most online recipes), metric cups (Australia, NZ, Canada), or UK/Imperial cups.
| Amount | US Cup(236.6 ml) | Metric Cup(250 ml) | UK Cup(284 ml) |
|---|---|---|---|
| ¼ cup | 30g | 31.7g | 36g |
| ⅓ cup | 40g | 42.3g | 48g |
| ½ cup | 60g | 63.4g | 72.1g |
| ⅔ cup | 80g | 84.5g | 96.1g |
| ¾ cup | 90g | 95.1g | 108g |
| 1 cup | 120g | 127g | 144g |
| 1½ cups | 180g | 190g | 216g |
| 2 cups | 240g | 254g | 288g |
Note: US cups (236.6 ml) are standard in most online recipes. Metric cups (250 ml, used in Australia, NZ, Canada) hold 5.7% more. UK/Imperial cups (284 ml) hold 20% more than US cups.
Measurement Note
Unsifted.
Need a Substitute?
Out of icing sugar? We've got 1 tested alternative with exact ratios.
Frequently Asked Questions
Why does icing sugar contain cornstarch?▼
Can I make icing sugar from granulated sugar?▼
Should I sift icing sugar before or after measuring?▼
How many grams in 1 cup of icing sugar?▼
Why is my icing grainy?▼
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Values are approximate and can vary depending on how the ingredient is measured. For precision baking, we recommend using a digital kitchen scale.