How much royal icing do I need?
Royal icing for a Christmas cake, a covered cake or a batch of cookies, with the recipe to weigh and the consistency to thin it to.
Free. No signup needed.The short answer
An 8 inch round cake with 3 inch sides takes about 570 g of royal icing for two coats, made from about 410 g of icing sugar. That is the Christmas cake number too, iced over marzipan. A 6 inch takes about 385 g, a 10 inch about 785 g, a 12 inch about 1 kg, and an 8 inch square about 725 g. Twenty four 3 inch cookies take about 430 g, roughly 14 g each.
How much royal icing do I need?
BakerInbox
What it is for
Flat icing over marzipan, the Christmas cake job
How you make it
Spreading a smooth coat over a cake or over marzipan.
Soft enough to cut
Royal icing to make
569 g
2 coats over top and sides
Icing sugar
410 g
Sift it. Every lump becomes a blocked nozzle
meringue powder
21 g
Dissolve into the water first
Water
138 g
Thin to 6 seconds, adding it a teaspoon at a time
Add 1 tsp of glycerine. It keeps the icing soft enough to cut cleanly, which is the difference between slicing a Christmas cake and chiselling one. Leave it out of anything you are piping, because it stops the icing setting hard enough to hold a shape.
The ten second test. Drag a knife through the surface and count how long the line takes to disappear. Ten seconds is flooding consistency. Fifteen holds an outline. Under about six it is too thin and will run off the edge. Add water a quarter teaspoon at a time, because royal icing goes from stiff to soup faster than anyone expects. The American standard, pasteurised, and the most forgiving of the three. Widely sold in the UK now too.
Icing sorted. BakerInbox costs the batch and tracks the order it belongs to.
Start free trialRoyal icing and consistency charts
| Cake size | Round | Square | Icing sugar, round |
|---|---|---|---|
| 6 in15 cm | 385 g14 oz | 490 g1 lb 1 oz | 275 g9.8 oz |
| 8 in20 cm | 570 g1 lb 4 oz | 725 g1 lb 10 oz | 410 g14 oz |
| 10 in25 cm | 785 g1 lb 12 oz | 995 g2 lb 3 oz | 565 g1 lb 4 oz |
| 12 in30 cm | 1.02 kg2 lb 4 oz | 1.30 kg2 lb 14 oz | 740 g1 lb 10 oz |
Two coats over the top and sides of a 3 inch tall cake, with an allowance for what sets hard in the bowl. A square cake takes more than a round of the same nominal size, because a square has more surface. For a Christmas cake this sits on top of the marzipan.
Consistency, and how to hit it
| Consistency | Line vanishes in | Water added | What it is for |
|---|---|---|---|
| Stiff peaks | It holds a peak | None | Flowers, snow peaks on a Christmas cake, and sticking decorations down. |
| Medium | 25 seconds | 3% by weight | Shells, borders, lettering and anything that has to hold its shape. |
| Outline | 15 seconds | 5% by weight | Piping the wall round a cookie before you flood inside it. |
| Flood, 10 second | 10 seconds | 8% by weight | Filling a cookie. A line drawn in it vanishes in ten seconds. |
| Flat coating | 6 seconds | 11% by weight | Spreading a smooth coat over a cake or over marzipan. |
Drag a knife through the surface and count how long the line takes to melt back flat. That is the test the ten second rule refers to. Add water a quarter teaspoon at a time, because royal icing goes from stiff to soup faster than anyone expects.
Made with BakerInbox. Free cake tools at bakerinbox.com/tools
How royal icing works
Covering a cake is a question of weight over surface, and icing cookies is a question of consistency, which is the part no chart answers.
How much
It follows the surface, not the recipe
A flat coat of royal icing is spread about 2 mm thick, which is roughly 1.7 g per square inch per coat. An 8 inch round with 3 inch sides has about 126 square inches of top and side, so two coats plus what sets hard in the bowl comes to about 570 g. A square of the same nominal size takes about 725 g, because a square has more surface. Measure across the top of the tin, the pan if you are in the US, and use the height of the cake as it will sit on the board. Fondant is worked out from the same area, so how much fondant to cover a cake lines up with these numbers if you are choosing between the two.
Christmas cake
Marzipan first, then two coats, then leave it alone
Royal icing goes over marzipan, never straight onto the fruit cake, or the oil and the fruit stain up through it. Give the marzipan a day or two to dry first. An 8 inch round takes about 570 g of icing across two coats, a 10 inch about 785 g and a 12 inch about 1 kg. Let the first coat dry for a full day before the second, and rough the last one up with the back of a spoon for snow peaks. In the US the same cake is a fruitcake and the icing over it is identical. For the cake underneath, how much fruit and marzipan a Christmas cake needs counts the schedule back from the day you need it.
Consistency
The ten second rule, and the four settings either side of it
Drag a knife through the surface and count how long the line takes to melt flat. Ten seconds is flood, for filling a cookie, and it takes about 8 percent of the icing's weight in extra water. Six seconds is a flat coating for a cake, at about 11 percent. Fifteen seconds is an outline, 25 seconds is medium for shells and lettering, and stiff peaks, with no water at all, is what holds a flower or a snow peak up. Add the water a quarter teaspoon at a time. Royal icing goes from stiff to soup faster than anyone expects, and the way back is more icing sugar.
What to make it with
Fresh egg white is raw, so keep it off anything you sell
Three ways to make it, and the difference matters once money changes hands. The traditional 570 g batch is 430 g of icing sugar and 82 g of fresh egg white, about two and a half large whites, and it is raw. It should not go near anyone pregnant, elderly, very young or unwell. Dried egg albumen and meringue powder are pasteurised and behave the same: the same batch is 420 g of icing sugar, 10 g of albumen and 82 g of water, or 410 g of icing sugar, 21 g of meringue powder and 82 g of water. Icing sugar is powdered or confectioners' sugar in the US, and dried albumen sells there as dried egg white powder.
Glycerine
One teaspoon per 500 g, and none of it in the piping bag
Royal icing sets like a helmet. On a cake that has to be cut, the knife skids and the slice shatters, so a teaspoon of glycerine per 500 g goes in to keep it soft. An 8 inch cake at 570 g takes about 1 teaspoon. Leave it out of anything piped: glycerine stops the icing setting hard enough to hold a shape, and a border made with it slumps overnight. It is spelled glycerin in the US and sits next to the food colouring. If the cake is getting a soft finish instead, work out how much buttercream for an 8 inch cake and how much filling for an 8 inch cake the same way.
FAQ
Common questions
How much royal icing do I need to cover an 8 inch cake?
About 570 g for two coats over the top and sides of an 8 inch round with 3 inch sides, which is roughly 410 g of icing sugar. A 6 inch takes about 385 g, a 10 inch about 785 g and a 12 inch about 1 kg. An 8 inch square takes about 725 g, because a square has more surface than a round of the same size.
How much royal icing for a Christmas cake?
About 570 g for a standard 8 inch round, spread over two coats on top of the marzipan. A 10 inch takes about 785 g and a 12 inch about 1 kg. Add a teaspoon of glycerine per 500 g so it stays soft enough to cut, and give each coat a full day to dry before the next one goes on.
What is the 10 second rule for royal icing?
Drag a knife through the surface and count. If the line disappears in about ten seconds, the icing is flood consistency and ready to fill a cookie. Getting there from stiff icing takes roughly 8 percent of its weight in extra water, added a quarter teaspoon at a time. Fifteen seconds is an outline and six seconds is a flat coating for a cake.
What consistency should royal icing be for cookies?
Two consistencies out of one batch: 15 second for the outline and 10 second for the flood. Pipe the wall first, let it crust for a few minutes, then flood inside it. That is about 5 percent water for the outline and 8 percent for the flood, thinned off the stiff batch as you go.
How much royal icing do I need for 24 cookies?
About 430 g, which is roughly 14 g a cookie for a 3 inch shape outlined and flooded. Twelve cookies, or biscuits as they are called in the UK and Ireland, take about 215 g. Move up to 4 inch shapes and the same 24 take about 765 g, because the icing follows the area and not the count.
Is royal icing made with raw egg white safe?
Not for a cake you are selling. Fresh egg white is raw, so it is off the table for anyone pregnant, elderly, very young or unwell. Dried egg albumen and meringue powder are pasteurised, whip up the same and keep better, which is why bakeries use them. In the US dried albumen is sold as dried egg white powder.
How long does royal icing take to dry?
The surface crusts in 15 to 30 minutes, but it is nowhere near dry through. Flooded cookies want 6 to 8 hours, or overnight, before they are stacked or bagged. A flat coat on a cake wants a full day before the next coat. Warm dry air speeds it up and a humid kitchen roughly doubles it.
Why is my royal icing not setting hard?
Usually glycerine, or too much water. Glycerine keeps icing soft on purpose, so a teaspoon per 500 g belongs on a cake that gets cut and never in a piping bag. A flat coating already carries about 11 percent water and simply takes longer than a stiffer mix. If it is neither, the kitchen is humid, so move it somewhere warm and dry.
Put every enquiry in one place too
Track every enquiry, order, and quote. Free for 14 days, no card required.