Keg Carbonation Calculator

How it works

This keg carbonation calculator (also searched for as a force carbonation chart or CO2 pressure chart for kegging) estimates the regulator pressure needed to force carbonate beer to a target CO2 level at a given temperature. Rather than using a single precise pressure/temperature formula, it works from a small hardcoded reference table of typical values — the same kind of table brewers use in a printed force carbonation chart — and interpolates between the nearest points, based on the reference figures published in Brewer’s Friend’s force carbonation chart.

The table covers beer temperatures from 0°C to 13°C across the rows, and target carbonation from 2.0 to 3.0 volumes of CO2 across the columns, with regulator pressure in kPa at each intersection. When your inputs fall between two listed points, the calculator uses bilinear interpolation — blending the two nearest temperature rows and the two nearest CO2 columns — to estimate a pressure in between:

Row bracket = the two table temperatures either side of your beer temperature
Column bracket = the two table CO2 volumes either side of your target
Interpolated kPa = blend of the four surrounding table values, weighted by how close
                    your inputs sit to each bracketing row and column
PSI = kPa ÷ 6.895

Because this is a reference table rather than an exact physical formula, the result is an approximate, typical value only. Your actual required pressure will vary with your specific regulator, the length of your gas line, and the composition of your beer — treat the number here as a sensible starting point on your keg pressure calculator, then fine-tune against your own gauge and taste-test the beer after it has sat at that pressure for a few days.

Worked example

Priya runs a small home kegging setup in her garage in Adelaide, South Australia. She’s just kegged a batch of American pale ale and keeps her keg fridge at a steady 4°C. She wants to hit American ale strength — 2.4 volumes of CO2 — which is one of the built-in presets on this calculator.

Both her temperature (4°C) and her target (2.4 volumes) land exactly on points in the reference table, so no interpolation is needed: the chart lists 95 kPa at that intersection, which converts to about 13.8 psi. Priya sets her regulator to 95 kPa, leaves the keg connected at serving temperature, and plans to taste-test it in about five days.

Her housemate Callum prefers a fizzier wheat beer, carbonated to 3.0 volumes, kept slightly warmer at 7°C. That falls exactly on the table too, giving a noticeably higher pressure:

Brewer	Temp	Target CO2	Regulator pressure
Priya (American ale)	4°C	2.4 vol	95 kPa (13.8 psi)
Callum (wheat beer)	7°C	3.0 vol	160 kPa (23.2 psi)

After five days, Priya checks her first pour — slightly undercarbonated — and nudges the regulator up a few kPa before testing again a couple of days later, treating the calculator’s figure as her starting point rather than the final word.