Ganache Calculator
Work out how much ganache you need to cover your cake — then get the exact chocolate and cream quantities to buy. Covers drips, crumb coats, smooth finishes and ganaching under fondant, in dark, milk or white chocolate.
How to make it
- 1
Finely chop the chocolate into small, even pieces and place in a heatproof bowl.
- 2
Heat the cream until it just starts to simmer — no rolling boil.
- 3
Pour the hot cream over the chocolate. Leave for 2 minutes without stirring.
- 4
Stir gently from the centre outwards until smooth, glossy, and fully emulsified.
- 5
Cool to a spreadable consistency before using — about 1 hour at room temperature, or 30 minutes in the fridge with occasional stirring.
Tips for best results
- Use good chocolate. Ganache is 2 ingredients — use couverture or baking chocolate, not chocolate chips (they contain stabilisers that resist melting cleanly).
- Weigh both ingredients. Ratios by weight are accurate; by volume they aren't.
- Test your drip. Before pouring over the whole cake, test one drip on a chilled, upside-down bowl. If it runs past halfway, the ganache is too warm — let it cool a bit longer.
- If it splits, add 1 tbsp warm cream and stir vigorously from the centre. Usually brings it back.
Ganache needed
1026g
Round 8" · 4" tall · under fondant
Ratio
3 : 2
chocolate : cream by weight
You need
Cream note: Use double cream (UK) or heavy cream (US) with at least 35% fat. Single/whipping cream will leave the ganache too soft.
Ganache quantity chart
Quantities in grams for a round cake 4 inches tall with three sponge layers. The full coat and under-fondant columns include ganache for two filling layers; the drip and crumb coat columns are the coating only. Every figure includes an allowance for what you lose to the bowl and the scraper.
| Cake size | Drip only | Crumb coat | Full coat + filling | Under fondant + filling |
|---|---|---|---|---|
| 6" round | 137g | 169g | 527g | 654g |
| 8" round | 195g | 246g | 841g | 1026g |
| 10" round | 260g | 333g | 1224g | 1474g |
| 12" round | 330g | 431g | 1677g | 2000g |
Square cakes of the same nominal size need about 27% more — switch the shape in the calculator above rather than adjusting by eye.
Ganache ratio chart
Chocolate to cream, by weight. Setting strength comes from cocoa solids, so the paler the chocolate the more of it you need for the same firmness. Always weigh both — ratios by volume are not accurate.
| What you are making | Dark | Milk | White |
|---|---|---|---|
| Drip | 1 : 1 | 2 : 1 | 3 : 1 |
| Filling / coating | 3 : 2 | 5 : 2 | 3 : 1 |
| Whipped frosting | 1 : 2 | 1 : 1 | 3 : 2 |
| Truffles / piping | 2 : 1 | 3 : 1 | 4 : 1 |
How these quantities are worked out
Most ganache charts online are someone's remembered numbers for one cake size. This one is calculated from the actual surface area of your cake, so it stays right when you change the height, the number of layers or the shape.
The sides of a round cake are the circumference multiplied by the height; the top is a circle. Multiply that combined area by how deep the ganache layer needs to be, then by the density of set ganache, which sits at about 1.1g per cubic centimetre — between chocolate at 1.3 and cream at 1.0.
Layer depth is what changes between finishes. A crumb coat is about 2mm, just enough to seal the sponge. A smooth exposed coat is around 3.5mm. Ganaching under fondant runs to about 5mm because you are building up a sharp edge that the fondant will sit against. Filling between sponges is thicker again at roughly 5mm per gap.
Everything except the drip figure then carries a 15% allowance. You genuinely do lose that much to the bowl, the spatula and the excess you scrape off while smoothing — and running 50g short halfway around a cake is a far worse outcome than having a little left over. Drips are excluded because you mix those in a jug and pour the lot.
Frequently Asked Questions
How much ganache do I need to cover an 8 inch cake?
A 4 inch tall, three layer 8 inch round takes roughly 1,000g of ganache to fill and coat under fondant, or about 840g for a smooth exposed coat with filling. If you only need a crumb coat, budget around 250g, and for a drip alone around 200g. Those figures already include an allowance for what you lose to the bowl and scraper.
How much ganache do I need for a drip cake?
Drips need far less than people expect. A 6 inch cake takes about 140g, an 8 inch about 200g, a 10 inch about 260g and a 12 inch about 330g. Make it in a jug rather than a bowl, and let it cool until it coats the back of a spoon before you pour.
What is the correct chocolate to cream ratio for ganache?
It depends on both the chocolate and the job. For dark chocolate, use 1:1 for drips, 3:2 for filling and coating, and 2:1 for truffles. Milk chocolate needs more chocolate because it has fewer cocoa solids — 2:1 for drips and 5:2 for filling. White chocolate needs the most, at 3:1 for both drips and filling.
Why does white chocolate ganache need more chocolate?
Setting strength comes from cocoa solids, and white chocolate has none — it is cocoa butter, milk solids and sugar. With the same amount of cream it stays pourable instead of setting firm, so the chocolate proportion has to rise to compensate. Milk chocolate sits between dark and white for the same reason.
How much ganache do I need under fondant?
Ganaching under fondant uses more than a normal coat because you are building up a thicker, sharper edge — budget around 5mm of ganache on the sides and top. On an 8 inch, 4 inch tall cake that is roughly 615g for the coat, plus around 410g if you are also filling between three layers.
Can I make ganache in advance?
Yes. Ganache keeps for up to two weeks in an airtight container in the fridge, or three months frozen. Bring it back to room temperature slowly and stir it smooth before use — microwaving in short bursts works, but heat it too fast and it will split.
My ganache split. Can I fix it?
Usually, yes. Add a tablespoon of warm cream and stir vigorously from the centre outwards until it comes back together. If that does not work, blitz it briefly with a stick blender, keeping the head submerged so you do not beat in air.
Does the calculator work for square cakes?
Yes. Switch the shape to square and enter the side width instead of the diameter. A square cake has noticeably more surface area than a round cake of the same nominal size, so it needs about 27% more ganache.
Covering the cake in fondant afterwards? The fondant calculator gives you the weight to buy and the diameter to roll it out to. If you are finishing with buttercream instead, use the buttercream calculator.
Making a celebration cake? You can design and print a matching custom cake topper at 300 DPI in your browser, free.