What pressure do I set to carbonate a keg?

Set the regulator to the pressure that holds your target CO2 volume at your beer’s temperature, then leave it connected. Colder beer needs less pressure for the same carbonation. For a typical American ale at 2.4 volumes and 38°F, that is roughly 10–12 psi. Enter your target and temperature above for the exact number.

What are CO2 volumes?

One volume of CO2 is one liter of dissolved carbon dioxide per liter of beer (at standard conditions). It is the standard way to specify carbonation: British ales sit around 1.5–2.0 volumes, most lagers and American ales 2.2–2.7, and wheat beers 3.3–4.5. Match the volume to the style, then find the pressure that holds it.

Why does temperature change the pressure I need?

CO2 dissolves more readily in cold liquid, so colder beer reaches the same carbonation at a lower pressure. Warm the same keg and CO2 comes out of solution, so you would need more pressure to hold it. That is why the calculator asks for beer temperature, not room temperature — set pressure for the temperature the beer is actually at.

How long does force carbonation take at set pressure?

Set-and-forget carbonation at serving pressure typically takes about 1–2 weeks to reach equilibrium. You can speed it up by chilling the keg, raising the pressure temporarily, and agitating — but that risks over-carbonating, so the patient route is more repeatable. Either way, the equilibrium pressure this tool gives is the one you settle on for serving.

Keg Carbonation Calculator

Pick your target CO2 volumes and beer temperature to get the regulator pressure to set for force carbonation.

Your Target

Target CO2 Volumes2.4 vol

Match to your style (see the table below).

Beer Temperature38°F

The temperature the beer is actually at in the keg.

Style	Typical CO2 volumes
British ales (cask-ish)	1.5–2.0
American ales, porters, stouts	2.2–2.7
Lagers, pilsners	2.4–2.6
Wheat beers (hefeweizen)	3.3–4.5
Belgian ales, saisons	2.9–4.0
Cider, sparkling / soda	2.5–3.5

Key Takeaways

To force-carbonate, set the regulator to the pressure that holds your target CO2 volume at the beer’s temperature, then leave it connected ~1–2 weeks.
Match volumes to style: British ales 1.5–2.0, American ales/lagers 2.2–2.7, wheat beers 3.3–4.5.
Colder beer needs less pressure for the same carbonation — set pressure for the beer’s temperature, not the room’s.
If the keezer temperature drifts, carbonation drifts with it, even at a fixed PSI.

Why pressure and temperature are one setting, not two

Carbonation is an equilibrium: at a given temperature, a given head pressure holds a specific amount of CO2 in solution. Change either and the carbonation changes. That is why "set it to 12 psi" is only half an instruction — 12 psi at 38°F is a well-carbonated ale, but 12 psi at 50°F is noticeably flatter. Always set pressure for the temperature the beer is actually at.

Keeping carbonation stable

Once you have dialed in the pressure, the thing that quietly ruins it is temperature drift: a keezer that warms on a hot day, a door left ajar, a failing thermostat. Because carbonation tracks temperature, a few degrees of drift shows up as foamy or flat pours. Monitoring keg and fermenter temperature continuously — and getting alerted before it drifts — is exactly what LoopString does for a brewery or a serious home setup.

Frequently Asked Questions

What pressure do I set to carbonate a keg?: Set the regulator to the pressure that holds your target CO2 volume at your beer’s temperature, then leave it connected. Colder beer needs less pressure for the same carbonation. For a typical American ale at 2.4 volumes and 38°F, that is roughly 10–12 psi. Enter your target and temperature above for the exact number.
What are CO2 volumes?: One volume of CO2 is one liter of dissolved carbon dioxide per liter of beer (at standard conditions). It is the standard way to specify carbonation: British ales sit around 1.5–2.0 volumes, most lagers and American ales 2.2–2.7, and wheat beers 3.3–4.5. Match the volume to the style, then find the pressure that holds it.
Why does temperature change the pressure I need?: CO2 dissolves more readily in cold liquid, so colder beer reaches the same carbonation at a lower pressure. Warm the same keg and CO2 comes out of solution, so you would need more pressure to hold it. That is why the calculator asks for beer temperature, not room temperature — set pressure for the temperature the beer is actually at.
How long does force carbonation take at set pressure?: Set-and-forget carbonation at serving pressure typically takes about 1–2 weeks to reach equilibrium. You can speed it up by chilling the keg, raising the pressure temporarily, and agitating — but that risks over-carbonating, so the patient route is more repeatable. Either way, the equilibrium pressure this tool gives is the one you settle on for serving.