FermentoryPriming sugar calculator
How much sugar to add at bottling so your beer, cider or seltzer carbonates properly — and doesn't gush or stay flat. Enter your batch, pick a style, and read off the grams.
Quick answer: a standard 19 L (5 gal) ale carbonated to 2.4 volumes, bottled at 20 °C, needs about 117 g of corn sugar or 107 g of table sugar — roughly 3.1 g per 500 ml bottle.
Work out your priming sugar
Temperature means the warmest your beer got after fermentation finished — that sets how much CO₂ is still dissolved in it.
How priming works, in one paragraph
At bottling, your yeast is still alive but has run out of food. Priming sugar is a measured last meal: the yeast eats it inside the sealed bottle, the CO₂ it makes has nowhere to go, and it dissolves into the beer. The right dose gives you the fizz the style needs. Too much gives you gushers or, in the worst case, burst glass — so you calculate, you don't guess.
The two numbers that matter
1. Target carbonation, in volumes of CO₂
"Volumes" is how brewing measures fizz: 2.4 volumes means the beer holds 2.4 times its own volume in dissolved CO₂. Every style has a customary range:
| Style | Volumes of CO₂ |
|---|---|
| British ales, stouts | 1.5 – 2.0 |
| Pale ale, IPA, most ales | 2.2 – 2.6 |
| Lager, pilsner | 2.4 – 2.7 |
| Cider (sparkling) | 2.5 – 3.0 |
| Hard seltzer | 2.8 – 3.2 |
| Wheat beer, Belgian styles | 3.0 – 4.0 |
2. The CO₂ already in your beer
Fermentation leaves some CO₂ dissolved in the beer, and how much depends on temperature: warm beer holds less, cold beer holds more. That's why the calculator asks for the warmest temperature the beer reached after fermentation ended. If it fermented at 18 °C but sat at 22 °C for a weekend, use 22 — CO₂ that escaped during the warm spell doesn't come back when you cold crash. The calculator uses the standard residual-CO₂ curve and the classic 15.2 g of corn sugar per gallon per volume.
Corn sugar or table sugar?
Both work. Corn sugar (dextrose) is the homebrew default because it dissolves easily and ferments completely. Plain table sugar (sucrose) is about 9% more potent by weight, so you need slightly less — the calculator shows both numbers. Whichever you use, dissolve it in a little boiled water, stir it gently into the bottling bucket, and bottle as usual.
Before you trust any number
- Make sure fermentation is actually done. Same gravity reading two or three days apart. Priming a beer that's still fermenting is the classic bottle-bomb recipe, no calculator can save you from that.
- Respect your bottles. Standard glass is happy to about 3 volumes. Above that, use thick Belgian-style bottles, swing-tops rated for it, or plastic PET.
- Mix evenly. Sugar solution poured in first, beer racked on top, one gentle stir. Uneven mixing means some bottles flat, some gushing.
The calculator that reads the recipe for you
The free Fermentory browser extension spots homebrew recipes on any blog or forum, scales them to your batch size, and carries calculators for ABV, IBU and carbonation — right in the popup.
＋ Add Fermentory to Chrome Free to install · optional one-time Pro upgradePriming sugar FAQ
How much priming sugar per 500 ml bottle?
For a typical ale at 2.4 volumes bottled at 20 °C, about 3.1 g of corn sugar per 500 ml bottle (2 g per 330 ml). That's the per-bottle version of the batch numbers above — batch priming in a bottling bucket is more consistent than dosing each bottle, but carbonation drops work fine if you prefer them.
Can I use normal table sugar instead of corn sugar?
Yes. Sucrose ferments just as completely and carbonates about 9% more per gram, so use slightly less — the calculator prints both amounts. Any flavour difference at priming quantities is essentially undetectable.
Which temperature do I enter?
The warmest the beer got after fermentation finished, not your bottling-day room temperature. CO₂ escapes from warm beer and doesn't return when you chill it, so the warm peak decides how much CO₂ is left in solution.
How long until the bottles are carbonated?
Two to three weeks at around 20 °C, then a few days in the fridge to settle. Cold rooms slow the yeast right down, so a bottle that seems flat after a week in a cool cellar usually just needs more warm time.