Converter
Why superfine sugar needs its own conversion
Superfine Sugar weighs about 190g per cup — in the middle of the density range for common baking ingredients. King Arthur Baker's Special Sugar (superfine/castor) = 190 g/cup. A cup is a unit of volume, so ingredients this different in density can't share one generic conversion factor — using a single "1 cup = X g" rule for everything will be wrong for at least some of what you cook.
Common measurement mistakes
- Using a generic cup-to-gram factor for every ingredient — superfine sugar does not weigh the same per cup as most other ingredients.
- Measurement note: King Arthur Baker's Special Sugar (superfine/castor) = 190 g/cup.
- Confusing weight ounces with fluid ounces when a recipe lists "oz" — they are not interchangeable.
Frequently asked questions
How many grams are in a cup of superfine sugar?
About 190g, king Arthur Baker's Special Sugar (superfine/castor) = 190 g/cup.
Does this conversion work for every brand or variety of superfine sugar?
It’s a close approximation based on King Arthur Baking. Minor variations in moisture, grain, or brand can shift the exact weight slightly, but this figure works well for everyday cooking and baking.