Ask a Vegan Baker

Great question marina.beijing!

I actually wasn't aware that the world had so many different definitions for the "measuring cup". How scary! I can't believe that there are so many recipes relying on different versions of the "cup" worldwide. That must mean that we're getting some pretty different results depending on where we are in the world and the recipes we're following! This just makes me want to move to the metric system of measuring liquids by milliliters and solids by grams that much faster. But there are advantages to using measuring cups and other scoopable units such as Tablespoons and teaspoons as I'll explain below.

As it turns out, it's difficult to determine the difference between the US Customary cup and the United States "legal" cup which are detailed on the Wikipedia page you referenced. If you were to take a cup and conduct your own measurements in milliliters, it would be extremely difficult to tell the difference: The US Customary Cup is 236.5 milliliters and the US "legal" cup is 240 milliliters. This works out to a difference of the "legal" cup being about 1.44% larger than the US Customary cup.

Since there are no details on what measuring system is used when buying measuring cups in the US, it's actually impossible to be positive to determine what kind of cup you're using unless you have lab-grade calibration devices. The good news is that since this variation is so small, it probably doesn't make much of a difference when baking things in normal batches in the home kitchen. When scaling up to industrial sizes though, it's definitely in your best interest to convert ingredients to metric volumes and weights for more consistency and user friendliness. Take it from me: I was burned from this very system back when I had a baking company and wanted to scale my recipes from my home version, up to a scale 10 times larger. I wish I had known about the pitfalls of the US volumetric baking measuring system back then.

The US and some other parts of the world favor "scoopable" measurements for two reasons:

1)
It works well enough in small amounts, such as in the home kitchen.

2)
It's actually more convenient and faster to just scoop a measurement and measure it while transferring it from the main storage container to your mixing bowl, as long as you're working in small, home kitchen-size batches.

In small amounts, such as normal home-size batches of baked goods, the scoop measurement of cups, Tablespoons and teaspoons works extremely well. But as I said earlier, if you're working in large amounts, you should definitely "ditch the US volumetric system" and convert to the more precise metric system of measuring by weight in grams and by volume in milliliters.

By the way, someday, I'll have every recipe on Veganbaking.net converted to have the option of using milliliters and grams but this is an extremely arduous undertaking.

Hope this clarifies things. Happy measuring!