The quick answer to this question is that it depends on the size of the cup you are using and what you are putting in it and possibly how tightly the ingredient is packed into the measuring cup.
This isn't a huge issue in recipes that measure dry ingredients by weight rather than volume but if you do find a great recipe that measures dry ingredients by volume keep in mind that there are a number of different sized cups and that a firmly packed cup will contain more than a loosely packed cup . European recipes don't usually suffer from these issues as liquids are generally measured by volume in mls and dry ingredients are specified by weight in grams.
US Cup
A US cooking cup has a volume of half a US pint or approximately 236mls .
Metric cup
Metric cups are commonly used in Australia and New Zealand and have a volume of 250mls.
If you find that you are following a recipe that calls for ingredients by weight and you don't have access to kitchen scales then you need to keep in mind that different ingredients have different densities and cups of these ingredients will have different weights as a result. A decent set of kitchen scales is IMHO a mandatory tool in any kitchen but if you do find yourself caught without them the conversion table below provides weight to volume conversions for some common ingredients.
| Ingredient | US cup | Metric cup |
| Flour | 120g | 125g |
| Granulated Sugar | 200g | 210g |
| Icing Sugar | 100g | 105g |
| Brown Sugar | 180g | 190g |
| Cornflour (corn starch) | 120g | 125g |
| Uncooked Rice | 190g | 200g |
| Uncooked Oats | 90g | 95g |
| Table Salt | 300g | 315g |
| Butter | 240g | 250g |
Quite often recipes found on websites are from the United States so butter measurements will be provided in sticks and tablespoons rather than by weight.
In the United States butter is sold by the pound and is divided up into 1/4 pound "sticks" which each weigh 4 ounces or approximately 115g. There are 8 tablespoons of butter in a "stick" each of which weighs 1/2 an ounce or approximately 15 grams.
