Keg Carbonation Calculator

How much CO2 dissolves into beer at a given pressure depends on temperature, so "set it to 12 PSI" is only correct advice for one specific beer temperature -- the same pressure carbonates a warmer keg less than a colder one, because CO2 solubility in liquid falls as temperature rises. This calculator solves that relationship in the direction brewers actually need: given your Target CO2 Volumes (how fizzy you want the finished beer) and Beer Temperature, it returns the Required PSI that reaches equilibrium at that volume, using the standard regression fit of the classic force-carbonation charts. Target CO2 Volumes is the stronger driver of Required PSI at typical serving conditions, but Beer Temperature is not a minor factor -- across the 30-55F kegging range, colder beer consistently needs less pressure than warmer beer for the same carbonation level, which is why "chill it down first" is standard kegging advice. At the cold, low-carbonation corner of the range the equilibrium pressure works out below atmospheric -- the beer already holds that many volumes with no applied pressure at all -- and Required PSI bottoms out at 1 PSI rather than going negative, because you still need positive head pressure to keep a CO2 blanket on the beer and to balance the line.

Days to Carbonate is deliberately a fixed one-to-two-week range rather than a computed number: on a regulator the keg's headspace pressure is held constant, so how fast the beer reaches equilibrium is governed by surface area, liquid depth and whether you agitate, not by which target you picked -- a 3.0-volume keg does not take meaningfully longer to reach 3.0 volumes than a 2.2-volume keg takes to reach 2.2. Burst Carbonation PSI and Duration describe the alternative shake-or-rock method: roughly 24 to 48 hours at a pressure well above your serving pressure, with agitation, after which you must relieve the keg and drop the regulator back to Required PSI or the beer will over-carbonate. The burst pressure shown is 30 PSI for ordinary targets, and higher whenever your target's own equilibrium pressure is close to or above 30 -- bursting below the equilibrium pressure would pull CO2 back out of the beer rather than force it in. Headspace volume, agitation technique, and CO2 line length once you're pouring all sit outside this calculator's scope -- they affect how quickly the keg actually reaches the calculated PSI's equilibrium and how the pour behaves at the tap, but none of them change the equilibrium pressure itself.