How much syrup does this cake need?
Soaking syrup worked out for your cake size and layers, with the sugar and water to weigh, and the flavour to put in it.
Free. No signup needed.The short answer
A three layer 8 inch round cake takes about 200 ml of soaking syrup at a standard soak, which is roughly 125 g of sugar and 125 ml of water at a one to one ratio. That is about 60 ml brushed over each layer, including the top one. A 6 inch takes about 115 ml, a 10 inch about 315 ml and a 12 inch about 455 ml.
How much syrup does this cake need?
BakerInbox
The cake to soak
How wet, and what with
Soak
Most cakes, most of the time
The standard soaking syrup. Water and sugar. Lets the sponge taste of itself.
Syrup to make
203 ml
3 layers to brush
On each layer
60 ml
Brush it on warm, right to the edge
Sugar
126 g
Weigh it, do not measure by cup
Water
126 ml
Heat until the sugar clears, no further
Bring the sugar and water to a simmer until the sugar has completely dissolved, then take it off the heat. Boiling it further turns it into a thick syrup that sits on top of the sponge instead of soaking in. Add any alcohol or extract once it is off the heat and cooled a little. Brush it on while the sponges are still slightly warm, and let them sit for ten minutes before you fill them.
Syrup sorted. BakerInbox keeps the recipe, the quote and the order together.
Start free trialSoaking syrup charts
| Cake size | Light | Standard | Generous | Per layer |
|---|---|---|---|---|
| 6 in (15 cm) | 68 ml2.3 fl oz | 114 ml3.9 fl oz | 182 ml3/4 cup | 34 ml1.1 fl oz |
| 8 in (20 cm) | 122 ml1/2 cup | 203 ml3/4 cup | 324 ml1 1/4 cups | 60 ml2.0 fl oz |
| 10 in (25 cm) | 190 ml3/4 cup | 317 ml1 1/4 cups | 507 ml2 1/4 cups | 94 ml3.2 fl oz |
| 12 in (30 cm) | 274 ml1 1/4 cups | 456 ml2 cups | 730 ml3 cups | 136 ml1/2 cup |
Three layers, so three faces to brush including the top one the frosting sits on. A four layer cake of the same size takes a third more. Figures include a small allowance for what stays in the bowl and on the brush.
Sugar and water, for an 8 inch cake
| Ratio | Sugar | Water | Makes | What it is for |
|---|---|---|---|---|
| Light (1:2) | 84 g3.0 oz | 168 ml3/4 cup | 203 ml (3/4 cup) | Thin and barely sweet. Good on an already sweet cake |
| Simple (1:1) | 126 g4.4 oz | 126 ml1/2 cup | 203 ml (3/4 cup) | The standard soaking syrup |
| Rich (2:1) | 168 g5.9 oz | 84 ml2.8 fl oz | 203 ml (3/4 cup) | Thick, keeps longer, use less of it |
Ratios are by weight, not by volume. Equal parts in a recipe usually means equal cups, which is not equal weights, and it is why two published simple syrups can taste noticeably different.
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How soaking syrup works
Syrup keeps a sponge soft for days rather than hours. The amount depends on the surface of each layer, which is why a single published quantity cannot be right for every cake.
What it is for
Syrup buys you time, not sweetness
A brushed sponge stays soft for days instead of hours, which is the whole reason bakeries do it. It is not there to make the cake sweeter, and a syrup you can taste as sugar has been laid on too heavily. The real use is anything made ahead: a cake baked on Thursday for a Saturday, or one that has been frozen and defrosted. If you are planning backwards from a date, the make-ahead planner works out which day to bake.
How much
It scales with the surface, not with the recipe
Syrup lands on the cut face of each layer, so a wider cake drinks more and a taller stack of thinner layers drinks more again. That is why one published quantity cannot serve every cake, and why every recipe post that gives you a cup of syrup is guessing on your behalf. Sixty millilitres over an 8 inch layer is the working figure, and everything above scales off it. Brush the top of every layer including the last one, because that face is what the frosting sits on.
The ratio
Equal parts by weight, not by volume
A one to one syrup means equal weights of sugar and water. Nearly every recipe on the web says equal parts and then measures in cups, which is not the same thing, because a cup of sugar weighs about 200 g and a cup of water weighs 236 g. That is why two published simple syrups can taste noticeably different. A lighter one to two syrup suits a cake that is already sweet. A rich two to one keeps for weeks in the fridge and you use less of it.
Method
Simmer until it clears, then stop
Bring the sugar and water together until the sugar has completely dissolved and the liquid goes clear, then take it straight off the heat. Boiling on from there drives off water and thickens it, and a thick syrup sits on top of the sponge rather than soaking in. Add alcohol or extract once it has come off the heat and cooled a little, or the alcohol carries the flavour away with it as it evaporates.
When to brush
Slightly warm sponge takes it best
Brush while the layers are still a little warm and give them ten minutes before you fill them. A cold sponge takes it more slowly and you will be tempted to add more than it needs. Over about 400 ml a clean spray bottle beats a pastry brush: it goes on faster and far more evenly, and it is what most decorators doing volume actually use. Once the layers are soaked, work out the filling and then the buttercream to cover it.
FAQ
Common questions
How much simple syrup do I need for an 8 inch cake?
About 200 ml, or three quarters of a US cup, for a three layer 8 inch round at a standard soak. That is made from roughly 125 g of sugar and 125 ml of water. A 6 inch takes about 115 ml, a 10 inch about 315 ml and a 12 inch about 455 ml.
What is the ratio of sugar to water for cake syrup?
One to one by weight is the standard soaking syrup: equal grams of sugar and water. One to two is lighter and suits an already sweet cake. Two to one is a rich syrup that keeps for weeks in the fridge, and you use noticeably less of it. Measure by weight, not by cups, because equal cups is not equal weights.
Do you brush syrup on a warm or cold cake?
Slightly warm. The sponge takes it in faster and more evenly, and you are less likely to overdo it. Let the layers sit for about ten minutes after brushing so the syrup spreads through before you fill and stack them.
How much syrup is too much?
If the sponge feels wet rather than moist, or the syrup pools on the plate when you cut it, that is too much. A generous soak is about 100 ml over an 8 inch layer. Past roughly double the standard amount, the crumb starts to break down and the cake will not hold up under fondant.
Can I make simple syrup without cooking it?
Yes, if you use a one to one ratio and hot water rather than boiling. Stir until the sugar has completely dissolved and let it cool. A rich two to one syrup does need heat, because that much sugar will not dissolve otherwise.
How long does cake soaking syrup keep?
A plain one to one syrup keeps about a month in the fridge in a sealed jar. A rich two to one keeps around six months, because the sugar concentration preserves it. Anything with fresh juice or dairy in it is a few days at most. Add alcohol and it keeps longer again.
What can I flavour the syrup with?
Replace some of the water rather than adding to it, or the syrup goes thin. Strong coffee in place of the water is the classic tiramisu soak. Lemon juice at about 15 percent, elderflower cordial at 20 percent with a fifth less sugar since it is already sweet, or rum and brandy at around 10 percent added off the heat.
Do you soak a cake before or after filling it?
Before. Brush each layer as you build, working from the bottom up, including the top face that the frosting will sit on. Once the cake is assembled and covered there is no way to get syrup into the middle of it.
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