You can make powdered sugar at home by blending granulated sugar with cornstarch in a high-speed blender until fine.
You run out of powdered sugar mid-recipe, stare at the box of granulated, and wonder if a blender could save you. The answer is yes — but only if you know the right ratio and the right tool. Skip the cornstarch and you’ll end up with clumpy, grainy sugar that wrecks your frosting.
This article walks through the standard ratio, shows which blenders actually work, and explains how to store the homemade version so it stays fluffy for weeks. No special equipment required beyond what’s likely in your kitchen right now.
What You Need: The Simple Ingredients List
Homemade powdered sugar needs exactly two things: granulated white sugar and cornstarch (or arrowroot powder). The standard ratio is 1 cup of sugar to 1 tablespoon of cornstarch. This combination creates the fine, fluffy texture you expect from a box of confectioners’ sugar.
Cornstarch acts as an anti-caking agent. It absorbs moisture from the air and prevents the ground sugar from clumping back together. Skip it, and your powdered sugar may clump within a day or two — especially in humid kitchens.
For a cornstarch-free version, blend granulated sugar alone. The result will be a fine powder, but it’s more prone to clumping over time. Arrowroot powder works as a 1:1 substitute for cornstarch if you prefer a different anti-caking agent.
Why Store-Bought Still Wins in Some Minds
Many home bakers assume store-bought powdered sugar is always better because of its impossibly fine texture and reliable performance. That assumption is worth unpacking. Here’s what commercial powdered sugar has going for it — and where homemade actually matches or beats it.
- Grind fineness: Commercial mills grind sugar to a particle size that home blenders can’t quite match. Homemade sugar is slightly grainier, which can matter in delicate glazes.
- Convenience: Opening a bag takes five seconds. Pulling out a blender and cleaning it takes five minutes. For small batches, that trade-off is often worth the store trip.
- Consistency: Store-bought cornstarch blends are rigorously uniform. Home blends can vary if the blender doesn’t pulverize evenly, which is why sifting is important.
- Freshness control: Homemade sugar is always fresh. That box in your pantry might be two years old and have absorbed off-flavors from the cabinet.
- Custom ratios: You control the cornstarch amount. Some recipes call for less or none, and store-bought doesn’t give you that option.
The gap between homemade and store-bought is smaller than most people think — especially once you learn the right blending technique.
The Step-by-Step Process
Pour 1 cup of granulated sugar and 1 tablespoon of cornstarch into a high-speed blender. A Vitamix or Blendtec works best, but a clean coffee grinder or spice grinder handles small batches well. A standard food processor may leave a slightly gritty texture because the blade can’t spin fast enough to pulverize the crystals fully.
Bring the blender speed up gradually — starting on low and ramping to high over about ten seconds. Blending at full power for one to two minutes is usually enough. Stop the blender and let the dust settle for about thirty seconds before removing the lid. Open the lid away from your face to avoid a sugar cloud.
If you’re curious about the finer details of the process, making powdered sugar covers the science behind the cornstarch ratio and why it matters for texture.
Equipment Comparison for Best Results
| Tool | Best For | Texture Quality |
|---|---|---|
| High-speed blender (Vitamix, Blendtec) | 1–2 cups sugar | Very fine, nearly commercial |
| Coffee or spice grinder | ½ cup or less | Fine but requires careful shaking |
| Standard food processor | Large batches | Coarse; often needs sifting |
| Mortar and pestle | Emergency small amounts | Labor-intensive, uneven |
| Rolling pin (bag method) | No electricity available | Coarse, clumpy |
For most home bakers, a high-speed blender is the sweet spot. If you make powdered sugar regularly, a dedicated spice grinder is a compact and affordable second option.
Yield and Storage
One cup of granulated sugar yields approximately 1.75 cups of powdered sugar. That’s enough to make a standard buttercream frosting or a thin glaze for a dozen doughnuts. If you need more, a double batch (2 cups sugar plus 2 tablespoons cornstarch) works well in a full-size blender — just don’t overfill.
- Sift before using: Homemade powdered sugar often contains a few larger particles. A fine-mesh strainer catches them and guarantees a smooth frosting or glaze.
- Store in an airtight container: Use a mason jar or a plastic container with a tight lid. Humidity is the enemy of fluffiness.
- Room temperature up to 2 weeks: In a cool, dry cabinet your homemade sugar stays clump-free for at least two weeks.
- Freezer up to 6 months: For longer storage, seal the sugar in a freezer-safe bag and press out as much air as possible before freezing. Thaw at room temperature before opening.
- Label the jar: Homemade powdered sugar looks identical to cornstarch or flour. A label prevents accidental grabs.
If you plan to store the sugar for more than a week, include the cornstarch — it’s what keeps the powder flowing freely over time.
Tips for Perfect Powdered Sugar Every Time
A few small adjustments separate a good batch from a great one. Start with cold sugar straight from the pantry — room temperature is fine, but avoid sugar that’s been sitting near the stove where it may have absorbed moisture. Do not overfill the blender; the sugar needs room to circulate, so fill no more than halfway.
Wait at least thirty seconds after blending before opening the lid. A fine sugar cloud can escape and coat your countertops. If you’re working without cornstarch, use the powdered sugar immediately or blend only what you need for a single recipe.
According to Love and Lemons in their cornstarch anti-caking agent guide, sifting is non-negotiable for frostings because even one or two unground crystals create a gritty mouthfeel. Take the extra ten seconds.
Cornstarch vs. Arrowroot vs. None: Quick Reference
| Anti-Caking Agent | Effect on Texture |
|---|---|
| Cornstarch (standard) | Helps prevent clumping; fine, powdery finish |
| Arrowroot powder | Works 1:1 with cornstarch; slightly less absorbent |
| None | Fine powder initially, but clumps quickly in humid air |
For most baking needs, cornstarch is the reliable choice. Arrowroot is a good alternative if you’re avoiding corn, though its moisture-fighting power is a hair weaker.
The Bottom Line
Making powdered sugar at home takes less than two minutes, costs a fraction of store-bought, and lets you control the anti-caking agent level. The standard 1-cup-sugar-to-1-tablespoon-cornstarch ratio works every time when you use a high-speed blender and sift the final powder. For frostings, glazes, and dusting, homemade sugar performs nearly identically to commercial bags.
If you bake often, a dedicated coffee grinder and a small jar of cornstarch in the pantry make it easy to whip up fresh powdered sugar on demand — no last-minute store trips needed.
References & Sources
- Bon Appétit. “What Is Powdered Sugar and Can You Make It” Powdered sugar (also called confectioners’ sugar or icing sugar) is simply granulated sugar that has been ground into a fine powder.
- Loveandlemons. “How to Make Powdered Sugar” Cornstarch acts as an anti-caking agent and an absorbent, preventing the sugar from clumping and absorbing moisture from the air.