How to Thicken Icing Sugar

If you need to save thin, runny icing sugar, don’t panic. Here are four different methods to thicken icing sugar using common kitchen ingredients.


1. Add Powdered Sugar

Powdered Sugar in strainer

The easiest way to thicken icing sugar is by adding (more) powdered sugar. Additional sugar will ‘soak up’ water, creating a firmer and thicker icing.


2. Use Cornstarch

One chef’s secret is to add cornstarch (a fine, white processed type of corn flour) to the icing mixture.

Dissolve a very small amount (i.e., one half of a teaspoon) of cornstarch in an equally small amount of boiling hot water. Quickly stir the cornstarch and water mixture to ‘cook-out’ the raw cornstarch taste.

Mix this into your icing mixture. As the icing cools down, the cornstarch will thicken the icing. Cornstarch is routinely used in kitchens as a thickening agent, often in sauces and soups.

In a pinch, plain or all-purpose flour can thicken icing sugar. Similar to the method above, the flour needs to be ‘cooked out’ before adding it to the sugar and water mixture.

This requires more heat, for a longer period of time. Use a saucepan on medium-high heat to quickly cook flour in a small amount of water before use as an icing thickener


3. Use Less Liquid and Don’t Add Food Dyes

icing sugar and water

In its simplest form, icing sugar is a mixture of two ingredients; sugar and water. Cutting back on the amount of liquid used is a quick technique to thicken any icing sugar.

Coloured food dyes are especially problematic – just a few drops of food colouring can noticeably thin out icing sugar.

By using less water, and cutting back on liquid food dyes, you’ll create a thicker icing sugar.

Wherever possible, use solid food colourants instead of liquids. These aren’t as vibrant and colourful, but will not impact icing consistency like liquid food dyes.


4. Add Butter or Other Fats

If you’re after a creamier, more spreadable icing, consider adding some fat to your mixture.

Butter is the go-to fat here. Adding butter thickens icing sugar, creating tasty buttercream.

Other fats can be used, including cream cheese (a healthier alternative to butter) or lard. Vegan and vegetarian fat alternatives could also be used to thicken icing sugar.