# Ultimate Guide to Carbonation and Priming
Master the art of priming and transform your homebrew from a flat experiment into a professional effervescent experience. Priming involves adding a precise amount of sugar so residual yeast in the bottle generates natural CO2 during a secondary fermentation. Too little sugar yields flat beer; too much creates dangerous pressure that can shatter bottles. The difference between the two is a few grams — which is why this calculator exists.
Critical Success Factors
- Temperature: Residual CO2 depends on the post-fermentation temperature peak.
- Precision: 5 extra grams per liter can be the difference between perfect carbonation and a geyser.
- Oxidation: Avoid splashing the liquid when transferring to mix the priming sugar.
# CO2 Volumes by Beer Style
Which Sugar Should You Choose?
Safety Warning
Pro Tip: Dissolve the Sugar Properly
Always boil your priming sugar solution (sugar dissolved in approximately 250ml of water per 20L batch) for 10 minutes before adding it to the beer. Boiling sanitizes the solution and ensures the sugar is fully dissolved and evenly distributed throughout the batch, preventing hot spots that cause uneven carbonation between bottles.Who is this tool for?
# Carbonation Science: Henry's Law
At its core, carbonation is governed by Henry's Law: the amount of gas dissolved in a liquid is proportional to the partial pressure of that gas above the liquid. When you prime a bottle and seal it, the yeast consumes the sugar and produces CO2 in a sealed environment. As pressure builds, the gas is forced back into solution. The temperature at which this equilibrium occurs determines the final carbonation level — which is why the fermentation temperature is the most critical variable in this calculator.
The residual CO2 in your beer before priming is not zero. Every beer holds dissolved CO2 from the fermentation process, and the amount retained depends on the highest temperature the beer reached. A beer fermented at 22°C holds significantly less residual CO2 than one that fermented at 16°C, even if both are now chilled. Failing to account for this residual leads to systematic over-carbonation — one of the most common mistakes among beginning homebrewers.