Cookies & Bars icing

Royal Icing Calculator

How much royal icing do I need for 24 cookies? About 1¾ cups to outline and flood 3-inch cookies, roughly one batch.

Decorating sugar cookies? Enter how many cookies and their size and get the cups of royal icing to make, the batch recipe, and the water to add for outline and flood consistency.

How to use it

  1. Enter the number of cookies, their size and how you'll decorate them.
  2. Make the batches shown and split them by color.
  3. Thin each color with the water amounts shown.

How it works

The batch is Wilton's meringue-powder royal icing: 4 cups (1 lb) of powdered sugar, 3 tbsp meringue powder and 5 tbsp warm water make about 3 cups.

For flooding, Wilton adds 1 teaspoon of water per cup of icing; for outlining, ⅛ teaspoon per cup of stiff icing.

How much icing each cookie takes is our own starting point, plus 15% for what stays in bags and tips.

Assumptions and limits

  • Meringue-powder royal icing, not raw egg whites.
  • Cookies about the size chosen, decorated on top only.
  • Icing kept covered so it doesn't crust.

Sources reviewed October 23, 2026.

Tips

  • Keep bowls and tools grease-free; fat stops royal icing setting.
  • Test flood icing: a line drawn through it should vanish in about 10 seconds.
  • Let flooded cookies dry 8 hours or overnight before stacking.

Recipes to try it with

Questions

How much royal icing do I need for 24 cookies?

About 1¾ cups to outline and flood 3-inch cookies, roughly one batch.

How do I thin royal icing for flooding?

Add about 1 teaspoon of water per cup, a little at a time.

How long does royal icing take to dry?

The surface sets in about an hour; let it dry fully, 8 hours or overnight, before stacking.