get FermentCalc

Force Carbonation Calculator

Enter your keg temperature and the carbonation level you want in volumes of CO2 to get the regulator pressure that equilibrates the beer there - plus the corn sugar rate that would prime the same beer in bottles.

Units
°F

Use the actual temperature where the keg sits, not the style guide: dissolved CO2 follows temperature and pressure, so a garage keg at 10 C needs different pressure than a fridge at 3 C for the same fizz.

Value must be between 23 and 203.

vol

Volumes of CO2 at serving: British ales 1.5-2.0, American ales and lagers 2.2-2.7, wheat and Belgian styles 3.3-4.5.

L
vol

Fermentation leaves about 0.85 volumes of CO2 dissolved at normal cellar temperatures; the sugar math subtracts it so the finished carbonation lands on target instead of overshooting.

Results

Value must be between 23 and 203.

How to use the force carbonation calculator

  1. Measure the real temperature where the keg sits, at beer height.
  2. Pick the target carbonation in volumes of CO2 for the style.
  3. Set the regulator to the resulting PSI and leave the gas connected.
  4. Wait five to seven days at that pressure for full equilibrium.

Dissolved CO2 is fixed by the pair of temperature and headspace pressure, not by time: hold the keg at the listed pressure and temperature and the beer converges exactly on target. The calculator uses the standard homebrewing equilibrium fit of the carbonation chart, the same numbers printed on every regulator chart. Serving pressure only changes the result if it changes temperature too.

P (psi) = -16.6999 - 0.0101059·T + 0.00116512·T² + 0.173354·T·V + 4.24267·V - 0.0684226·V², T in °F, V in volumes

Kegging skips bottle priming entirely, but if you split a batch into bottles the priming sugar calculator sizes the sugar side, and the ABV calculator confirms the strength of what goes into the keg.

Frequently asked questions

Why does warmer beer need more pressure to carbonate?

CO2 is less soluble as temperature rises, so the same pressure dissolves fewer volumes in a warm keg. To reach the same carbonation at 12 C you need roughly double the pressure required at 3 C. That is why the calculator asks for temperature first - the chart is a trade-off between the two.

How long until the keg reaches the target carbonation?

About five to seven days at the set-and-forget pressure for a full 19 L keg, longer if the keg is cold or half full. Rolling or shaking a keg at serving pressure speeds the surface exchange and can cut it to a day or two, but the final level is still set by temperature and pressure, not by how long you shake.

Can I crank the regulator to 30 PSI to carbonate faster?

You can burst-carbonate at high pressure for 24-48 hours, but the beer will overshoot unless you then drop to the equilibrium pressure for the temperature and wait. Overshoot pours as all foam. For predictable results, set the calculator's PSI and wait - the gas has nothing else to do but dissolve.