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Caster sugar:
grams to cups.
Caster sugar weighs 200 g per cup — the same as granulated sugar — because the density difference from the smaller crystal size is negligible at cup scale. Where caster sugar differs is in how quickly it dissolves and aerates in creaming.
Caster Sugar: grams to cups
Approximate cup fractions for common gram amounts. Based on 200 g per cup.
| Grams | Cups (approx) | Decimal |
|---|---|---|
| 25 g | ⅙ | 0.13 |
| 50 g | ¼ | 0.25 |
| 100 g | ½ | 0.50 |
| 150 g | ¾ | 0.75 |
| 200 g | 1 | 1.00 |
| 250 g | 1 ¼ | 1.25 |
| 500 g | 2 ½ | 2.50 |
Caster Sugar: cups to grams
Based on 200 g per cup.
| Volume | Grams (g) |
|---|---|
| 1 cup | 200 g |
| ¾ cup | 150 g |
| ½ cup | 100 g |
| ⅓ cup | 67 g |
| ¼ cup | 50 g |
| 1 tbsp | 13 g |
| 1 tsp | 4 g |
Convert caster sugar instantly
Smaller crystals, same cup weight, better dissolving
Caster sugar (called superfine sugar in the US) is granulated sugar ground to a finer crystal size — roughly half the diameter of standard granulated. The smaller crystals pack very slightly more densely, but the difference at 1 cup is only about 2–4 g, which is within normal measurement variation. For conversion purposes, 200 g per cup applies to both. Where the crystal size matters is in how quickly the sugar dissolves: caster sugar dissolves faster in cold liquids, creams more smoothly into butter for sponge cakes, and produces a finer, more uniform texture in meringues. In applications where undissolved sugar crystals would be a textural problem — pavlova, génoise, pound cake — caster sugar is worth using even if the weight is identical.
When to use caster vs granulated by weight
Since both weigh 200 g per cup, most weight-based recipes don't distinguish between them. The choice matters most in British-style baking: Victoria sponge recipes specifically call for caster sugar because the fine crystals cream into butter more thoroughly, creating the fine crumb that defines the cake. For American-style cookies and most cakes, granulated sugar is fine. If you're following a UK recipe by weight and it calls for caster sugar, the gram quantity is correct for granulated too — just expect a marginally coarser texture from granulated if the specific recipe was developed with caster.
Frequently asked questions
- How many grams is 1 cup of caster sugar?
- 1 cup of caster sugar weighs 200 g — the same as granulated sugar. The finer crystal size doesn't meaningfully change the cup weight.
- Can I substitute granulated sugar for caster sugar at the same gram weight?
- Yes — at the same gram weight, granulated sugar and caster sugar are interchangeable in most recipes. Granulated may leave slightly more texture in meringues or cold beverages where fast dissolving matters.
- How many cups is 150 g of caster sugar?
- 150 g ÷ 200 g/cup = 0.75 cups — exactly ¾ cup.
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