Priming sugar for carbonation
How much sugar to add when bottling.
When bottling, the wanted saturation is created with sugar: the yeast finishes it inside the sealed package, and the CO₂ stays in the beer. The calculator works out how much sugar to add, allowing for residual gas.
Calculator
Fill in the fields to see the result
Why residual gas matters
Before packaging, the beer already holds 0.8–1.0 volume of dissolved CO₂ — more the warmer the fermentation was. Priming sugar is added only for the difference between the target and this residual, so the same recipe needs different amounts of sugar for beer fermented at 18 °C and at 24 °C.
Ignore the residual gas and it is easy to overcarbonate the bottles — all the way to gushers on opening and bursting containers.
How much sugar to add
Sucrose is fully fermented by yeast, so the calculation comes down to the mass that will produce the required volume of gas. A useful rule of thumb is about 4 grams of sucrose per litre for each volume of CO₂.
sucrose = 4.01 g/L · volume · (target − residual)
Target saturation by style
| Style | CO₂ volumes |
|---|---|
| English bitter | 1.5–2.0 |
| Stout | 1.8–2.2 |
| American IPA | 2.2–2.6 |
| Lager | 2.4–2.7 |
| Wheat beer | 3.0–3.6 |
Substituting for sucrose
- Dextrose (glucose) ferments completely, but you need about 10 % more by weight than sucrose.
- Maltodextrin and dry malt extract give less carbonation per gram and add flavour.
- Honey and syrups contain water and have variable fermentability — they are poor choices for precise carbonation.
- Dissolve the sugar in a small amount of water, boil and cool it, then add it to the full volume before packaging and stir gently without splashing.