Ingredient Guide
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Caster Sugar ingredient guide →1 ounce of Caster Sugar in cups
Also known as superfine sugar, castor sugar, baker's sugar.
1 ounce of caster sugar = 0.15 US cups. That's based on a 190 g per cup baseline. Because caster sugar can shift with packing and crystal size, weighing is usually more accurate than measuring by volume.
Answer
0.15 cups
Based on caster sugar density of 0.8 g/ml
Sources: King Arthur Baking, USDA FoodData Central
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Find a substitute →How many cups is 8 oz, 16 oz, or 32 oz of caster sugar?
Packages of caster sugar are usually labeled by weight. These are weight ounces converted at 190 g per cup — not fluid ounces.
| Package size | US cups |
|---|---|
| 4 oz | 0.60 cups |
| 8 oz | 1.2 cups |
| 12 oz | 1.8 cups |
| 16 oz | 2.4 cups |
| 24 oz | 3.6 cups |
| 32 oz | 4.8 cups |
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Caster Sugar substitutions
Start with Granulated Sugar using 1:1 by weight, then see the full substitute hub for more tested options.
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Caster Sugar substitute for cookies
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Caster Sugar substitute for cookies →Quick Reference Table
| ounces | cups |
|---|---|
| 1 ounces | 0.15 cups |
| 2 ounces | 0.30 cups |
| 4 ounces | 0.60 cups |
| 8 ounces | 1.2 cups |
| 16 ounces | 2.4 cups |
Figures use the US cup (236.6 ml).
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Ingredient-specific, density-based conversions for baking
1 ounces of Caster Sugar equals 0.15 cups
Ingredient-specific · density-based
Cup size
Based on us cup (236.6 ml) · density data from baking references and our own measurements.Advertisement
What the sources say caster sugar weighs
Published values, quoted at the exact measure each source lists. Sources round differently and assume different fill techniques — which is why they rarely agree to the gram.
| Source | Listed measure | Weight |
|---|---|---|
| King Arthur Baking | 1 cup (Baker's Special / superfine) | 190 g |
| King Arthur Baking | 1 cup (granulated, for comparison) | 198 g |
CupOrGram standardizes on 190 g per cup (12 g per tablespoon, 4 g per teaspoon) and uses that single value on every page — how we reconcile the sources.
Why this conversion varies
Caster Sugar can pack very differently depending on crystal shape and moisture.
- Fine vs coarse crystals change how much fits in a cup.
- Packed measurements can be much heavier than loose fills.
- This page uses a consistent 190 g per cup baseline for repeatable conversions.
Why this conversion matters
Caster Sugar directly affects sweetness, spread, and browning. A small conversion mismatch can shift texture and caramelization, especially in cookies and frostings.
Practical baking use
Finely milled granulated sugar — the default baking sugar in the UK and Australia. Sold as superfine or Baker's Special sugar in the US. Use this conversion for cookies, syrups, and frostings where sugar balance affects spread and set.
- Packed and loose measurements are not interchangeable.
- Adjust in small steps if your ingredient is unusually moist or dry.
FAQ
How much is 1 ounce of caster sugar in US cups?
1 ounce of caster sugar is 0.15 US cups using a 190 g per cup baseline.
Is 8 oz of caster sugar the same as 1 cup?
1.2 cups — 8 oz by weight of caster sugar is not 1 US cup. A cup of caster sugar weighs 190 g (6.7 oz). Ounces on this page are weight, not fluid ounces — the "8 oz = 1 cup" rule only holds for water-like liquids.
Is it better to weigh caster sugar for baking?
Usually yes. Weight-based measuring reduces shifts from packing and crystal size, so your results are more repeatable.
Related links for Caster Sugar
Recipe Context for Caster Sugar
For cookies: sugar ratio drives spread and caramelization.
For cakes: sugar level affects tenderness and moisture retention.
For frostings: weight gives repeatable texture batch to batch.
Common Pitfalls
- Switching brands without re-checking weight can change texture and bake time.
- Using volume-only measurements for dense ingredients can overshoot recipe targets.
- Packed vs unpacked sugar measurements are not interchangeable.
Brand Variance Example
Baseline on this page: 1 cup caster sugar = 190g. Real-world range can shift by about 8% because granule size, packing, and moisture level shift how much sugar fits in a cup.
Example for 2 cups: baseline 380g, common range 350g-410g. If your bake is texture-sensitive, start with the lower bound and adjust after a test batch.
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