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Powdered sugar:
grams to cups.
Powdered sugar (confectioners' sugar, icing sugar) weighs 113 g per cup — one of the lightest sugar measurements because the fine powder and added cornstarch create lots of air gaps. Sifting reduces the weight per cup further still.
Powdered Sugar: grams to cups
Approximate cup fractions for common gram amounts. Based on 113 g per cup.
| Grams | Cups (approx) | Decimal |
|---|---|---|
| 25 g | ¼ | 0.22 |
| 50 g | ½ | 0.44 |
| 100 g | 1 | 0.89 |
| 150 g | 1 ⅓ | 1.33 |
| 200 g | 1 ¾ | 1.77 |
| 250 g | 2 ¼ | 2.21 |
| 500 g | 4 ½ | 4.42 |
Powdered Sugar: cups to grams
Based on 113 g per cup.
| Volume | Grams (g) |
|---|---|
| 1 cup | 113 g |
| ¾ cup | 85 g |
| ½ cup | 57 g |
| ⅓ cup | 38 g |
| ¼ cup | 28 g |
| 1 tbsp | 7 g |
| 1 tsp | 2 g |
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Sifted vs unsifted: a major source of variation
Powdered sugar clumps aggressively in the bag and forms hard compacted lumps over time. A cup measured from clumped, unsifted sugar can weigh significantly more than 113 g. A cup sifted before measuring can weigh as little as 95–100 g. Recipes for frostings and glazes that call for "1 cup powdered sugar, sifted" intend the lighter measurement. When a recipe just says "1 cup powdered sugar," without specifying, it typically means measured after gentle loosening — not packed from a clumped bag. For perfect buttercream or fondant where sugar quantity directly controls sweetness and consistency, weighing 113 g per cup eliminates this ambiguity.
Cornstarch content and its effect on density
Commercial powdered sugar contains 3–5% cornstarch, added to prevent caking. This cornstarch is part of the 113 g/cup measurement — it's not a separate ingredient. When you substitute homemade powdered sugar (granulated sugar blended until fine) in recipes, you're omitting the cornstarch and working with a slightly denser powder that may weigh closer to 120–125 g per cup. In frostings, the cornstarch also absorbs a small amount of moisture, helping the frosting hold its shape. For recipes where that holding property matters — like a piped cake border — use commercial powdered sugar rather than the blended granulated substitute.
Frequently asked questions
- How many grams is 2 cups of powdered sugar?
- 2 cups of powdered sugar weigh 226 g (2 × 113 g). If the recipe says "sifted," the same 2 cups may weigh closer to 190–200 g.
- How many cups is 500 g of powdered sugar?
- 500 g ÷ 113 g/cup ≈ 4.42 cups — just over 4 cups and 6 tablespoons.
- Is powdered sugar the same as confectioners' sugar?
- Yes — they are different names for the same product. In the UK and Australia, the same ingredient is called icing sugar. All have approximately 113 g per cup.
Common substitutions
| Substitute for powdered sugar | Ratio | Notes |
|---|---|---|
| Blended granulated sugar | 1:1 by weight | Blend granulated sugar in a food processor until fine. Omits the 3–5% cornstarch; frostings may be slightly less stable. |
| Caster sugar (for frostings) | 1:1 by weight | Fine crystals dissolve well but will give a grainier texture than powdered. Works only in cooked frostings, not raw buttercream. |
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