Beer Priming Sugar Calculator

The Physics of Bottle Conditioning

Bottle conditioning is the process of creating 'natural' carbonation by adding a precise amount of sugar (priming sugar) to fermented beer right before sealing it in bottles. The residual yeast performs a 'mini-fermentation' inside the bottle, trapping the resulting CO2. This is a high-stakes calculation: too little sugar results in flat beer, while too much sugar creates 'bottle bombs'—dangerous glass explosions caused by excessive internal pressure.

Volumes of CO2

Carbonation is measured in 'Volumes'. One volume is a specific amount of CO2 gas dissolved into an equal volume of liquid at a specific temperature.

• British Cask Ale: 1.5 - 2.0 Volumes (Low carbonation)
• Standard American Ale: 2.4 - 2.6 Volumes (Medium carbonation)
• German Hefeweizen: 3.3 - 4.5 Volumes (High carbonation)

The Role of Temperature

The amount of sugar needed depends on the Highest Temperature reached during fermentation. Cold beer naturally holds more dissolved CO2 than warm beer. If your beer finished at 70°F, it already contains about 0.85 volumes of CO2. If it finished at 32°F (Cold Crash), it contains 1.7 volumes. You only need to add sugar to make up the difference between what is already there and your target.

The Formula

The amount of sugar is calculated based on the batch volume and the delta between current and target CO2 volumes.

(Note: Table sugar (sucrose) and Corn sugar (dextrose) have different fermentability rates and require different weights to achieve the same result.)