Gelling calculator
Gelatin, agar and xanthan by the weight of your liquid
Say how much liquid you have and what texture you want: the dose comes out in grams, with the page it came from. The sheet-to-powder conversion, which is where nearly every recipe goes wrong, comes with it.
It sets in the mould and comes out whole: firm panna cotta, aspic, fruit jelly.
How much to use
| Agent | Amount | % of liquid |
|---|---|---|
| GelatinGels · No boiling needed · Holds to 37 °C | 4.00 g | 0.8%Myhrvold & Bilet, cap. "Custards and Pies" — "Raspberry Panna Cotta" |
| Agar-agarGels · Must boil · Sets at 35 °C · Holds to 85 °C | 2.50 g – 5.00 g | 0.5% – 1%Esteve, Scoolinary, Additional material, slide 34 |
| Kappa carrageenanGels · Must boil · Sets at 50 °C · Holds to 70 °C | 0.50 g – 5.00 g | 0.1% – 1%Esteve, Scoolinary, Additional material, slide 43 · Myhrvold & Bilet, cap. "Custards and Pies" — "Raspberry Panna Cotta" |
| Gellan gumGels · Must boil · Sets at 70 °CDoes not melt once set | 3.50 g – 10.00 g | 0.7% – 2%Esteve, Scoolinary, Additional material, slide 39 |
| MethylcelluloseGels · No boiling needed · Sets at 60 °CSets with heat | 10.00 g – 12.50 g | 2% – 2.5%Esteve, Scoolinary, Additional material, slide 55 |
| PectinGels · Must boil | 5.00 g – 10.00 g | 1% – 2%Esteve, Scoolinary, Additional material, slide 21 |
Iota and kappa go together in this recipe: the mixture lands between the soft gel of one and the firm gel of the other.
- Gelatin — Melts at 37 °C — body temperature, which is exactly why it dissolves in your mouth. No use for anything that will be served hot.
- Agar-agar — It has to boil to hydrate, which rules it out for raw preparations and cold soups. In exchange it holds to 85 °C once set — and that number is the one figure on this page where two independent works say exactly the same thing.
- Kappa carrageenan — Makes firm, brittle gels, of the moulded-jelly kind. It sets fast, at 50 °C — work hot and keep it moving.
- Gellan gum — The only one here that does not melt once set. It goes in the oven, takes a blowtorch and works as a pastry filling — no other agent on this page does that.
- Methylcellulose — It works backwards from everything else: it gels when heated and melts when cooled. That is what makes fried gel possible. It dissolves cold, at 3–4 °C, and sets at 60 °C — with only ten degrees between melting and gelling, the narrowest margin on the page.
- Pectin — The same one from jam, here at gelling doses. Low-methoxyl pectins give soft gels; high-methoxyl ones give the firm gel of a pâte de fruit.
Sheet or powder: converting by Bloom
The recipe calls for powder and you have sheets — or the other way round. The grade changes the weight, and the source publishes the exact formula instead of the “one sheet per spoonful” guess.
- Use
- 4.00 g
- The published dose is in Knox powder, 225 Bloom
- 4.00 g
new weight = original weight × original Bloom ÷ new Bloom · Bloom 225 → 225
| The gelatin you have | Bloom | g per sheet |
|---|---|---|
| Bronze | 125–155 | 3.3 |
| Silver | 160 | 2.5 |
| Gold | 190–220 | 2 |
| Knox (powder) | 225 | powder |
| Platinum | 235–265 | 1.7 |
Look at the table: the weaker the sheet, the heavier it is. Bloom times grams per sheet lands between 400 and 460 across all four grades — sheets are made to carry roughly the same gelling power, which is why recipes written in “number of sheets” work at all. That reading is ours, not a claim the book makes.
The book also says gold and platinum can replace Knox powder directly. By its own formula that is off by about 10% each way. It is a kitchen shortcut; here we use the formula.
Check the dose you already used
Give the liquid, the agent and how much you weighed. If the dose does not match the texture you were after, the page says which texture it does match — because that is usually the answer: no arithmetic went wrong, a different product came out.
Dose against the liquid
In the source: 0.7%
Myhrvold & Bilet, cap. "Sauces" — "Onion Fluid Gel", cap. "Sauces" — "How to Make Gels and Fluid Gels"With this agent, that same dose also lands in: Demoulded gel.
What changes the firmness
The dose is the start. Whatever else is in the liquid changes the gel, and McGee gives the direction of each — direction, not a number: anyone publishing “add 20%” would be inventing it.
- Sets softer
- Salt — it interferes with the bonds between gelatin molecules.
- Sets firmer
- Sugar — it pulls water away from the gelatin. Fructose is the exception.
- Sets firmer
- Milk.
- Sets firmer
- Alcohol — until it reaches 30–50% of the gel, when the gelatin precipitates into grains and the gel is lost.
- Sets softer
- Acid below pH 4 — vinegar, fruit juice, wine.
Salt and acid are compensated for with more gelatin. Tannins from tea and red wine cloud the jelly by precipitating the gelatin itself.
How we know the rule holds
The source confirms itself three times on the same page, and that is what this calculator rests on.
The dose: its panna cotta holds 530 g of liquid — 30 g milk, 300 g cream, 200 g raspberry purée — and the table prints 4.3 g of gelatin. The rule of 0.8 g per 100 g gives 4.24 g: the book rounded its recipe up. What that pins down is what it counts as liquid — with the sugar in it would be 4.84 g, and with only the dairy, 2.64 g.
The Bloom formula: the printed example converts 2.6 g of Knox into 3.7 g of silver, and 2.6 × 225 ÷ 160 = 3.66. The printed substitutions for silver (1.1 g) and bronze (1.3 g) per 100 g of liquid come out of the same arithmetic, starting from the 0.8 g.
The fluid gel: the onion sauce takes 3.5 g of agar for 500 g of onion milk, and the recipe’s own scaling column prints 0.7% — which is where a fluid gel falls between the thick sauce and the purée of the instruction page.
Spherification
How much liquid you are spherifying, and by which of the two techniques. The product dose and the bath dose come out separately, because they are percentages of different things.
The flavoured base that becomes the sphere.
The bath is reusable: make a volume that fits your container.
The alginate goes in the liquid and the sphere drops into a calcium bath. The calcium moves in and does not stop: in about 30 minutes the sphere gels through and becomes a single texture. Caviar is eaten straight away.
In the liquid
- Sodium alginate
- 2.50 g – 5.00 g0.5% – 1%
- Sodium citrate(optional)
- 0.50 g – 1.00 g0.1% – 0.2%
- Xanthan gum(optional)
- 0.00 g – 1.50 g0% – 0.3%
In the bath
- Calcium chloride
- 5.00 g0.5%
What the direct method will not take
- Fat.
- Dairy, or anything that already carries calcium — the calcium inside would react with the alginate too early. This is why the course makes its Parmesan sauce by the reverse method.
- Pure alcohol above 30° proof.
- An acid medium: the alginate precipitates. The sodium citrate on the list is there precisely to correct the acidity of the base.
- The reaction cannot be stopped. Rinsing the sphere does not help: the calcium is already inside.
The course’s own recipes
The two caviar recipes in the course itself land at 0.489% and 0.495% alginate — consistent with each other and a hair below the 0.5% floor it states. Not a contradiction: it is where the chef actually works inside the band she publishes, at the bottom of it. And across the eight reverse-spherification recipes, the gluconolactate and the xanthan stay inside the course’s generic bands without a single exception.
About the source for this part
The spherification doses and the new agents come from course material — two courses by Rais Esteve, head of R&D at 100%Lab, published by Scoolinary. Course material is not a bibliography, and this page would rather say so than disguise it: no book pagination, no bibliography of its own, and not free to open. We cite by document and slide number.
Nor is it a flawless source, and the defects are on the record because they change how it should be read. The slide giving the direct-spherification proportions prints "xanthan" twice on the same line. And the methylcellulose slide writes "2%, 2 grams per liter" — 2% of a liter is 20 g, an error of one order of magnitude. That it is an error and not another convention, the course itself proves: it gets the same conversion right for kappa and for gellan. We use the percentages and drop the parenthesis.
What carries confidence in the rest is internal coherence: the course’s recipes obey the proportions it states, in all eight that can be checked. It is the same test that validated Wybauw for ganache and Corvitto for gelato.
A note about the source
Our copy of *Modernist Cuisine at Home* is a scan with optical character recognition, and OCR gets names right while destroying numbers — ours turns “500 mL” into “S00 mL” in places.
So every dose on this page was checked against the image of the printed page, not the extracted text. The same check was repeated on the four brine recipes that already used this book: all four were correct.
Glossary
- Hydrocolloid#
- A long molecule that disperses in water and traps the liquid in a mesh, thickening or gelling it. Gelatin, agar, xanthan and carrageenan are all hydrocolloids; starch is one too, by a different route.Myhrvold & Bilet, cap. "Sauces" — "How to Make Gels and Fluid Gels" · McGee, cap. 11, "Plant Gums"
- Fluid gel#
- A gel that sets solid and is then blended back into a liquid. Thick on the spoon and thinning in the mouth, with a creamier texture than a sauce thickened with starch or xanthan.Myhrvold & Bilet, cap. "Sauces" — "How to Make Gels and Fluid Gels", cap. "Sauces" — "Onion Fluid Gel"
- Bloom strength#
- A measure of gelatin’s gelling power, named after Oscar Bloom, who invented the device that measures it. The higher the number, the firmer the gel for the same weight. Sheets sold as bronze, silver, gold and platinum correspond to rising Bloom ranges.Myhrvold & Bilet, cap. "Custards and Pies" — "Working with Gelatin" · McGee, cap. 11, "Jelly Consistency"
- Spherification#
- A technique built on alginate, extracted from brown seaweeds, which gels only in the presence of calcium. A calcium-free alginate solution is dripped or injected into a calcium solution and gels on contact, forming spheres or threads with a thin skin and a liquid centre.McGee, cap. 11, "Carrageenan, Alginates, Gellan"
Frequently asked questions
How many gelatin sheets equal one envelope of powder?
It depends on the grade of the sheet, which is why the conversion exists. The source’s formula is weight × the Bloom you have ÷ the Bloom the recipe calls for. A gold sheet (190–220 Bloom) weighs 2 g; a bronze one (125–155) weighs 3.3 g — and the two gel almost identically, because the weaker sheet is made heavier on purpose.
Can I swap gelatin for agar gram for gram?
No. Different doses and different behaviour: agar has to boil to hydrate, sets firmer and holds to 85 °C; gelatin melts at 37 °C, which is exactly what makes it dissolve in your mouth. For a demoulded gel the source uses 0.8% gelatin; for the vegetarian version of the same panna cotta, 0.15% agar with 0.12% xanthan.
Does xanthan gum gel?
No. It thickens: it gives the liquid body without letting it set, and it works cold, with no boiling. If you want a gel that comes out of a mould, that is gelatin, agar or carrageenan.
Why is there no spherification here?
Because no book on our shelf publishes a dose for sodium alginate or calcium chloride. McGee describes the mechanism and the glossary entry is here, but a number without a source does not go on screen — and that number lives in volume 4 of Modernist Cuisine, which we do not have.
What counts as “liquid”?
Whatever the source counts. In its panna cotta that is the milk, the cream and the fruit purée — 530 g in all — and the sugar and salt stay out. The 0.8% rule applied to those 530 g returns exactly the 4.3 g of gelatin the recipe prints.
Sources for this calculator
Every number comes from a single book, and the page says so. McGee is here for what he does better than anyone: explaining why salt, sugar and acid change the gel — without publishing how much, which he honestly does not have.
Modernist Cuisine at Home
Myhrvold & Bilet · The Cooking Lab
cap. "Custards and Pies" — "Raspberry Panna Cotta" · cap. "Sauces" — "How to Make Gels and Fluid Gels" · cap. "Sauces" — "Onion Fluid Gel" · cap. "Sauces" — "How to Make Full-Flavored Pan Gravy" · cap. "Custards and Pies" — "Working with Gelatin" · cap. "Custards and Pies" — "Firm Pastry Cream"
Esteve, Scoolinary · Scoolinary
Additional material, slide 34 · Additional material, slide 50 · Additional material, slide 43 · Additional material, slide 39 · Additional material, slide 55 · Additional material, slide 21
Spherification Techniques (Basic e Advanced)
Esteve, Scoolinary · Scoolinary
Basic — Additional material, slide 8 · Basic — Additional material, slide 10
On Food and Cooking
McGee · Scribner
cap. 11, "Jelly Consistency" · cap. 11, "Carrageenan, Alginates, Gellan"