Ganache calculator
The ratio changes with the texture you want
Tell it how much cream you have and what the ganache is for. You get the chocolate and butter from Wybauw’s table, the water the recipe carries, and the shelf life — the number almost no ganache recipe ever prints.
The soft ganache that goes inside a chocolate shell. The shell holds the shape, so the filling can stay soft.
The table was written for dark couverture with 36 to 38% cocoa butter.
What to weigh
Chocolate300 g
- Butter
- 35 g
- Chocolate against cream
- 120%
- Finished ganache
- 585 g
- Water in the recipe
- 156 g · 27%
Summed from the published contents: 60% of the cream and 17% of the butter. It is the quantity that decides shelf life, and the lever the book tells you to pull to extend it.
Three weeks, and freezing does not change that
3 weeksWybauw translates water activity into time: products between 0.85 and 1 Aw, "such as many ganache recipes", last three weeks. Between 0.6 and 0.85, like buttercream, they reach about three months. Below 0.6 nothing grows at all.
And the trap: "Freezing never extends shelf life." The example is the book’s own — a praline with three weeks left, frozen for eight months, still has three weeks once thawed. The freezer stops the clock; it does not wind it back.
Wybauw, "Improved shelf life in practice", "Freezing correctly"Three weeks, and freezing does not change that
The figure almost no ganache recipe prints, and what makes it a figure rather than a guess.
What grows in each band
- above 0.9
- bacteria, including salmonella and listeria
- above 0.8
- fungi thrive
- above 0.75
- yeasts grow
- above 0.6
- osmophilic yeasts and moulds
- below 0.6
- nothing lives; microbiological spoilage is excluded
Measured water activity, by ingredient
- Cream 35% and 40%
- 1.00
- Butter
- 0.985
- Condensed milk
- 0.99
- Sweetened condensed milk
- 0.84
- Fondant sugar
- 0.80
- Commercial marzipan
- 0.72
- Dark, milk and white chocolate
- 0.35
This calculator does not work out the Aw of your recipe, and that is deliberate. Water activity is not an average of the ingredients’ Aw: it depends on what is dissolved in the free water, on the molecular weight of those substances, on temperature and on packaging — the book lists those factors itself. What can honestly be summed is the water, and that is what the page does.
How the calculation works
Ganache is an emulsion of water in fat, and the two do not bind on their own. The bridge is dry substance: the sugars and cocoa powder in the chocolate. Three quantities in balance, not two — which is why changing the brand of chocolate changes the result without the ratio changing, and why "1 to 1" describes nothing on its own.
Wybauw’s table resolves that by destination: each texture has its own proportion, measured against 100 of soft substance. The calculator stores the published ratio and multiplies by the cream you have. Nothing more — the arithmetic is short, and what it is worth lives in the table, not in the sums.
The book prints the same table twice, as ratios and as percentages, and that is what makes a transcription from a noisy PDF trustworthy: the four percentage rows sum to exactly 100 and land within a point and a half of the ratios. We keep the ratios, because the percentages were adjusted to close at 100 — on the piping row, 100:120:25 gives 40.8 / 49.0 / 10.2 and the book prints 40 / 50 / 10.
The water comes from two published figures: cream is 60% water and butter is 17%. Adding them gives the quantity that decides shelf life. The Aw does not: it is measured, not deduced, and the measured table sits on the page whole rather than becoming an estimate of ours.
Common questions
What is the ratio for ganache?
There is not one: there is one per texture. For 100 g of cream, Wybauw uses 110 g of chocolate in a truffle ganache, 120 g plus 14 g of butter in a moulded praline, 120 g plus 25 g of butter for piping, and 130 to 180 g plus 24 to 30 g of butter for cut pralines. The "1 to 1" you find online is one of the four, not the rule.
How long does ganache keep?
Three weeks. Wybauw is blunt about it: products with a water activity between 0.85 and 1, "such as many ganache recipes", have a shelf life of only three weeks. And freezing does not extend it — a praline with three weeks left, frozen for eight months, still has three weeks once thawed.
Does white chocolate change anything?
It does: white needs about 2% extra cocoa butter over the recipe to reach the same texture, because its fat is 8% milk fat inside the 36% total. The chocolate proportion itself does not change.
Does this work for any chocolate?
The table was written for dark couverture with 36 to 38% cocoa butter and milk couverture with 36 to 37% total fat. The author himself warns that couverture far outside that range gives "a completely different result", and publishes no correction. Chocolate at 70% cocoa solids or more carries too much cocoa butter and needs less chocolate — how much less, he does not say.
Why did my ganache split?
Because the balance between water, fat and dry substance left its range. Ganache is an emulsion of water in fat, and the two do not bind on their own: the sugars and dry cocoa are the bridge. With too little or too much of any of the three, the mixture curdles, turns grainy, or comes out too firm or too liquid.
One source, and why
This is the only calculator on the site resting on a single book. On a site whose argument is showing disagreement, that has to be written down.
| Topic | What we have | What the calculator does |
|---|---|---|
| Ratio by texture | Wybauw only. The natural counterweight would be Greweling, and the copy we have is an image scan: 200 pages with no text layer. | Gives Wybauw’s table and says it comes from one author. When Greweling becomes verified text, the disagreement lands here. |
| The cut-praline range | The book itself gives 130 to 180 of chocolate and 24 to 30 of butter — a wide range, and the percentage it prints alongside matches the bottom of it. | Shows the whole range rather than a midpoint. Averaging a range the source left open would be our invention. |
| Couverture outside the range | Wybauw states his own — 36 to 38% cocoa butter — and warns that outside it the result changes completely. He publishes no correction. | States the range and states that we do not have the correction. Estimating it is exactly what this site does not do. |
| Water activity | The book’s table is measured, ingredient by ingredient. There is no published formula for deducing a recipe’s Aw from it. | Shows the measured table and sums the water, which is summable. Does not compute Aw. |
Glossary
- Ganache#
- A filling based on water and fat, in which the two only stay together because of the dry substance — sugars and cocoa powder — bridging them.Wybauw, "Balancing ganache recipes"
- Soft substances#
- The base of 100 in the proportion table: cream, milk, liqueur, invert sugar, glucose. Not a synonym for cream, even if cream is the usual case.Wybauw, "Balancing ganache recipes" — tabela de proporções médias
- Couverture#
- Chocolate with enough cocoa butter to run thin when melted. The proportions on this page were written for couverture at 36 to 38% cocoa butter.Wybauw, "Balancing ganache recipes"
- Water activity (Aw)#
- The fraction of a food’s water that is free rather than bound to sugars, salts or proteins. Micro-organisms use the free water, which is why Aw predicts spoilage better than total water content.Wybauw, "Improved shelf life in practice"
- Pre-crystallising#
- Bringing the cocoa butter in the ganache to its stable crystal form before it sets. A ganache that is not pre-crystallised has a shorter shelf life, dries out faster, loses its aromas sooner and may turn grainy.Wybauw, "Optimising the quality of the ganache" — Emulsifying, homogenising
- Fat bloom#
- The whitish film that appears on chocolate when fat migrates and recrystallises. Wybauw lists non-pre-crystallised ganache among the reasons it shows up sooner.Wybauw, "Optimising the quality of the ganache" — Emulsifying, homogenising
Source for this calculator
One book, and the page says so rather than disguising it. Wybauw is the technical reference on filled chocolates, and both the proportion table and the water-activity data — which nothing else on the shelf carries — are his.
Fine Chocolates: Great Experience
Wybauw · Lannoo
"Balancing ganache recipes" — tabela de proporções médias · "Balancing ganache recipes" · "Improved shelf life in practice" · "Improved shelf life in practice" — Average water activity for frequently used ingredients · "Freezing correctly"