Sugars & Syrups
Convert ounces of caster sugar to cups
One ounce of caster sugar weighs about 0.126 cup, and half a ounce comes to roughly 0.063 cup. Enter any amount below to convert it, or use the chart further down as a quick reference while you cook.
1 oz of caster sugar =
0.126 cup
About 1/8 cup in recipe notation
- ml
- 29.8
- tbsp
- 2.02
Caster Sugar: 225 g per US cup · FAO / INFOODS density database. Caster (superfine) sugar has smaller crystals that pack tighter than granulated sugar, so a cup weighs more.
Full caster sugar chart →Caster Sugar at a glance
Every number on this page comes from a single figure: 225 grams per US cup (FAO / INFOODS density database).
- 1 cup
- 225 g
- 1 tablespoon
- 14.1 g
- 1 teaspoon
- 4.69 g
- 1 cup in ounces
- 7.94 oz
- 100 g in cups
- 0.444 cups
- Density
- 0.95 g/ml
ounces to cups chart for caster sugar
Print it, screenshot it, or bookmark this page — these are the amounts recipes ask for most often.
| Ounces (weight) | Cups (US) | Tablespoons (US) | Millilitres |
|---|---|---|---|
| 0.5 oz | 0.063 cup | 1.01 tbsp | 14.9 ml |
| 1 oz | 0.126 cup | 2.02 tbsp | 29.8 ml |
| 2 oz | 0.252 cup | 4.03 tbsp | 59.6 ml |
| 3 oz | 0.378 cup | 6.05 tbsp | 89.4 ml |
| 4 oz | 0.504 cup | 8.06 tbsp | 119 ml |
| 5 oz | 0.63 cup | 10.1 tbsp | 149 ml |
| 6 oz | 0.756 cup | 12.1 tbsp | 179 ml |
| 8 oz | 1.01 cup | 16.1 tbsp | 238 ml |
| 12 oz | 1.51 cup | 24.2 tbsp | 358 ml |
| 16 oz | 2.02 cup | 32.3 tbsp | 477 ml |
How this conversion is calculated
Volume-to-weight conversions are only as good as the density behind them. We treat caster sugar as 225 g per US customary cup, which works out to 0.951 g/ml. From there:
- Your ounces figure is converted into millilitres or grams using standard unit sizes (oz = 28.3 g).
- The density above bridges volume and weight in whichever direction you need.
- The result is rounded the way a cook would round it — to the nearest gram, or to a usable fraction such as 1/2 cups.
Measuring caster sugar accurately
Caster (superfine) sugar has smaller crystals that pack tighter than granulated sugar, so a cup weighs more.
If a recipe matters to you — bread, macarons, anything with a tight hydration or ratio — weigh it. A £10 digital scale removes the single largest source of variation in home baking, and it is faster than washing three measuring cups.
When cups are fine
- Liquids measured in a proper jug, where volume is the honest unit anyway.
- Forgiving savoury cooking: soups, stews, stir-fries, marinades.
- Small amounts of leaveners and spices, as long as you use level spoons.
Frequently asked questions
How many cups are in 1 ounce of caster sugar?
1 ounce of caster sugar is 0.126 cup. This is based on a density of 225 g per US cup.
How many cups are in 2 ounces of caster sugar?
2 ounces of caster sugar is 0.252 cup, and 0.063 cup for half a ounce.
How much is 100 g of caster sugar in cups?
100 g of caster sugar is about 1/2 cups. Weight is always the more reliable measurement, so use a scale when the recipe gives grams.
Why do other sites give a different number for caster sugar?
Caster (superfine) sugar has smaller crystals that pack tighter than granulated sugar, so a cup weighs more.
Do UK and Australian cups give the same result?
No. A US customary cup is 236.6 ml, a metric cup used in Australia and New Zealand is 250 ml, and an old UK imperial cup is 284 ml. Our default is the US cup, but you can pick metric cups in the converter.