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Forced Carbonation Pressure Calculator

Set your regulator to hit a target CO2 level.

How it is calculated

The tool uses a regression fitted to CO2 solubility data that homebrewers commonly use, with beer temperature T in degrees Fahrenheit and target carbonation V in volumes of CO2:

P = −16.6999 − 0.0101059·T + 0.00116512·T² + 0.173354·T·V + 4.24267·V − 0.0684226·V²

P is gauge pressure in PSI (above atmospheric). It is shown with two decimals. If the formula gives a negative number, the tool shows 0.00 PSI. Volumes must be above zero. The fit is meant for beer at normal serving and cold-crash temperatures; the tool does not check the temperature range, so an out-of-range temperature still produces a number. Set the regulator to this pressure and give the keg time to reach equilibrium.

Worked example

Beer at 38 °F in the keg, target 2.5 volumes of CO2.

Terms: −16.6999; −0.0101059 × 38 = −0.3840; 0.00116512 × 38² = 1.6824; 0.173354 × 38 × 2.5 = 16.4686; 4.24267 × 2.5 = 10.6067; −0.0684226 × 2.5² = −0.4276.

Sum ≈ 11.25, so set the regulator to 11.25 PSI.

At the same temperature a lower target of 2.2 volumes needs only about 8.09 PSI.

Try this example →

Common mistakes

  • Entering the temperature in Celsius. The field is Fahrenheit, so a 3.5 °C beer typed as 3.5 returns 0.00 PSI; 38 °F is the correct entry.
  • Using the room temperature of the fridge door or the keg's surface instead of the liquid temperature. A few degrees warmer changes the pressure noticeably.
  • Confusing volumes of CO2 with percent or grams per litre. Typical beer targets are a few volumes, such as 2.2 to 2.8.
  • Reading the result as absolute pressure. It is gauge pressure, which matches the regulator dial.
  • Setting the pressure and expecting instant carbonation. The beer needs days at that pressure to reach equilibrium, and a long beer line or serving pressure may differ from the carbonation pressure.

About this calculator

Forced carbonation dissolves CO2 into beer under pressure rather than waiting for natural bottle conditioning, and the pressure needed to reach a target carbonation level (measured in volumes of CO2) depends heavily on the beer's temperature, because colder liquid holds more dissolved gas at a given pressure — the relationship is captured in CO2 solubility tables or the corresponding regression formula that homebrewers and commercial brewers both rely on.

Homebrewers with a kegging setup and CO2 tank use this to dial in a regulator to a precise PSI for a target style — British ales are typically carbonated to lower volumes than German lagers or Belgian styles, for instance — and getting the pressure-to-temperature match right avoids both flat beer and over-carbonated, gushing pours.

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