Keg CO2 Pressure Calculator

At a fixed temperature, the equilibrium CO2 dissolved in beer rises with the head pressure, following Henry's law. Colder beer holds more CO2 at the same pressure. To force carbonate, you set the regulator to the pressure that, at your keg temperature, gives your target carbonation volumes and leave it to equilibrate.

Typical targets vary by style: many ales sit around 2.2 to 2.5 volumes, lagers a touch higher, and highly carbonated styles above 3.0. The right volume is a style and taste choice, so it is a user-editable input. One volume of CO2 means one liter of CO2 gas dissolved per liter of beer at standard conditions.

It uses a widely used polynomial fit to standard carbonation tables, with keg temperature in degrees Fahrenheit and the target in CO2 volumes, returning regulator gauge pressure in psi. It is an empirical approximation of the equilibrium chart, accurate across normal serving and force-carbonation conditions, not a first-principles thermodynamic derivation.

CO2 solubility is strongly temperature dependent. Warm beer needs much higher pressure to hold the same carbonation, and may foam when poured. Most setups keep the keg cold (around 38 deg F) and set the matching pressure. Always enter your actual keg temperature, not room temperature.

Set-and-forget force carbonation at serving pressure typically takes one to two weeks to reach equilibrium; shaking or higher-pressure methods are faster but need care. This calculator gives the equilibrium pressure for your target, not the time, which depends on method, agitation and temperature.