Unlike granulated sugar, powdered sugar dissolves easily at room temperature, with no real agitation needed. That makes it great for glazes, buttercreams, frostings, icings, mousses—basically anywhere where the mixture won’t be cooked or where a smooth texture with no hint of graininess is especially vital.
Some of our most beloved royal icing and glaze recipes, in fact, are simply a combination of powdered sugar and a small amount of liquid. Sometimes that liquid is milk or cream or buttermilk, other times it’s water or lemon juice or strong coffee or tea. When you whisk these two ingredients together, a marvelously viscous, shiny, pourable glaze forms, aided by the thickening, gelatinizing power of cornstarch, one of two essential ingredients in powdered sugar. (Ever played the Ooblek game and made that mysterious cornstarch-and-water concoction? Well, some genius put all those childish science experiments to use and invented The Glaze. Props.)
Powdered sugar is what brought you the glaze on that lemon pound cake.
Powdered sugar also comes in handy in no-bake candies (fudge or Buckeyes, for example), where it brings that melt-in-your-mouth sweetness, and you’ll also see in some meringue recipes, where, thanks to the cornstarch, it acts as a stabilizer.
How to make powdered sugar
Now to answer the burning question: Can you make your own powdered sugar if you don't have any lying around? The answer is YES!
To make homemade powdered sugar, you’ll need two ingredients: granulated sugar and cornstarch. The magic ratio is 1 cup granulated sugar to 1 tablespoon cornstarch. Combine the two in a high-powered blender like a Vitamix, a food processor, or spice grinder, then blitz away until you have a soft, powdery consistency—the total time could be several minutes, depending on the power of your machine.
I wouldn’t recommend using a spice grinder to make larger batches of the powdery stuff, as it can get a bit messy, and in most instances where you’ll need several cups, it’s probably worth it to go get yourself a box from the grocery store. But when you only need a few tablespoons for dusting over brownies (yet another great use for the powdered stuff), this trick will save you from an unnecessary trip.
Can you use granulated sugar in place of powdered sugar?
In most cases, no. If you’re making a recipe in which powdered sugar is a vital ingredient (cookie dough, for example), stick with powdered sugar or risk getting a final product that doesn’t meet your expectations. But if you are going to try your hand at substituting, you’re more likely to get decent results if you substitute by weight rather than by volume. (Powdered sugar weighs 113 grams per cup whereas granulated sugar weighs 200 grams.)
One last thing! You can absolutely forego powdered sugar altogether for sweetened whipped cream. I don’t know about you, but my mother always swore by adding powdered sugar to her cream before whipping it. And as is the case with most mothers, she is always right, so I never gave it another thought. Until one day I grew up, started to use all my powers of critical thinking, and realized that there is absolutely no reason granulated sugar doesn’t work just as well when whipping cream. Assuming that you're going to Whip It Good, there’s no chance the granulated sugar will remain undissolved, and therefore will sweeten your cream just as well as powdered. I promise.
So yes: You need it. Sometimes. And yes, you can you forego in some situations. AND you can make it yourself if you have to. Now you have all the answers. So what're you waiting for? Go make those outrageously good Brown Butter Wedding Cookies already!
The cookies in question:
Six-ingredient cookies for people who don't think they can bake cookies.
This article was originally published in 2018 and was updated by Sarah Jampel in 2021.
