Carbonation calculator: CO2 volumes, psi and temperature
To carbonate water to 3.5 volumes of CO2, a lively sparkling-water level, set the regulator to about 21.5 psi (1.48 bar) with the water at 4 °C (39 °F). The same fizz needs about 29 psi (2.0 bar) at 10 °C (50 °F) and 43 psi (3.0 bar) at 20 °C (68 °F), because cold water holds more gas. Pick your drink and temperature below for your own number, or enter the pressure you already use to see how fizzy it gets.
Blue Fizz ClubCarbonation card
Set the regulator to
21.5psi
That is 1.48 bar on the gauge, for 3.5 volumes of CO2 at 4 °C (39 °F), at sea level.
Target
3.5 volumes (6.9 g CO2 per litre)
Drink temperature
4 °C (39 °F)
CO2 pressure, absolute
36.2 psia (2.50 bar)
Air pressure at your altitude
14.7 psi (1.01 bar) at sea level
Sparkling water or club soda
3.5 volumes is inside the 2.5–3.5 range. UF/IFAS lists club soda and tonic water at 2.5–3.5 volumes.
Chill the drink to the temperature first, then hold this pressure until it stops taking up gas: the figure is the balance point, not a quick setting.
A keg with a carbonation stone gets there within hours, and shaking speeds it up (UF/IFAS).
Sugar and alcohol make a drink hold a little less CO2 than plain water.
Show the numbers
Regulator pressure by drink temperature
°C
°F
psi
bar
0 °C
32 °F
17.2
1.18
2 °C
35.6 °F
19.3
1.33
4 °C
39.2 °F
21.5
1.48
6 °C
42.8 °F
23.8
1.64
8 °C
46.4 °F
26.2
1.81
10 °C
50 °F
28.8
1.98
12 °C
53.6 °F
31.4
2.17
14 °C
57.2 °F
34.2
2.36
16 °C
60.8 °F
37.1
2.56
18 °C
64.4 °F
40.2
2.77
20 °C
68 °F
43.4
2.99
22 °C
71.6 °F
46.7
3.22
24 °C
75.2 °F
50.1
3.46
How much pressure does carbonation need?
A drink in a closed bottle or keg trades CO2 with the gas above it until the two balance. How much ends up dissolved depends on two things only: the pressure of CO2 in the headspace and the temperature of the drink. More pressure pushes more gas in; colder liquid holds more of it. That balance is Henry's law, and it is what this calculator solves:
Here p is the CO2 pressure in bar, measured from a vacuum (so 1.01 bar is added to what your regulator shows at sea level), and T is the drink temperature in kelvin. The 0.034 mol per kg per bar and the 2400 K temperature factor are CO2's Henry's-law constants in the NIST Chemistry WebBook, and 22.414 litres is the volume of one mole of gas at 0 °C and 1 atmosphere. One "volume" means the drink holds its own volume of CO2 measured at 0 °C and 1 atmosphere, which is about 1.96 g of CO2 per litre.
We checked the equation against Table 2 of the University of Florida's IFAS Extension guide to carbonating at small scale, which gives volumes for water at 0, 5, 10 and 15 °C and 0 to 40 psi. Every one of its 36 values is within 1.1 % of ours. Sugar and alcohol lower the solubility a little, so the figures are a touch generous for sweet sodas and for kombucha.
The gauge sets the pressure; the temperature decides how much of that gas the drink keeps.
How fizzy should it be?
Carbonation is a matter of taste, but published levels give a sensible starting point. UF/IFAS lists these, and notes that most people can't detect less than about 0.6 volumes and that more than 8 volumes burns the tongue and makes a bottle a hazard:
Drink
Volumes of CO2
Regulator at 4 °C (39 °F)
Club soda and tonic water
2.5–3.5
11–21.5 psi (0.77–1.48 bar)
Lemon-lime sodas
2.5–3.5
11–21.5 psi (0.77–1.48 bar)
Colas
3.5–4
21.5–26.7 psi (1.48–1.84 bar)
Champagne, for comparison
4.6–6
Made in the bottle, not at home on a regulator
There is no published standard for kombucha or water kefir, so pick by taste. For an apple drink in the cider style, US tax law offers a useful band: wine stops counting as "still" above 0.392 g of CO2 per 100 ml (2.0 volumes), and hard cider is capped at 0.64 g (3.3 volumes).
Worked examples
Lively sparkling water from the fridge: 3.5 volumes at 4 °C needs an absolute CO2 pressure of 3.5 ÷ 1.40 = 2.50 bar. Take away the air's 1.01 bar and the regulator reads 1.48 bar, or 21.5 psi.
The same water at room temperature: at 20 °C one bar dissolves only 0.87 volumes, so 3.5 volumes needs 4.00 bar absolute: 43 psi on the gauge. That is why chilling first saves gas and gives finer bubbles.
"I always set 30 psi": at 4 °C that settles at 4.3 volumes, sharper than most colas; at 20 °C it reaches only 2.7.
In Denver, at about 1,600 m (5,280 ft): the air presses down with about 83.5 kPa instead of 101.4, so the gauge needs about 2.6 psi more for the same fizz: 24.1 psi for 3.5 volumes at 4 °C.
How to force carbonate at home
Chill the drink to the temperature you will carbonate at, ideally fridge-cold, and use a keg or a carbonation cap on a plastic soda bottle that is rated for the job.
Purge the air from the headspace with CO2: air in the headspace takes up pressure without adding fizz.
Set the regulator to the pressure above and leave it connected. UF/IFAS says a keg with a carbonation stone can be fully carbonated within hours, and that shaking speeds it up a lot.
Serve or bottle from the pressurised vessel; once opened, the drink starts losing gas to the air.
At altitude
A regulator gauge shows pressure above the surrounding air, while the drink responds to the total pressure. Higher up, the air pushes less, so you need a little more on the gauge for the same fizz. The calculator uses NASA's standard-atmosphere formula for air pressure by height. If you also cook or boil up there, High Nestle works out boiling points at altitude.
Common mistakes
Carbonating warm and serving cold. A drink carbonated at room temperature with a cold-drink pressure ends up flat; set the pressure for the temperature the drink is at while it takes up gas.
Cranking the pressure to speed things up and forgetting it. Left connected, the drink keeps absorbing until it matches the higher pressure and comes out over-carbonated.
Reading the chart for beer. Brewing charts are made for beer; plain water and sweet sodas behave a little differently, which is why this page starts from water.
Using a bottle not made for pressure. Decorative glass, jars and thin bottles can burst. Use kegs, carbonation caps on plastic soda bottles, or bottles sold for carbonated drinks, within their maker's limits.
Pressure safety. CO2 cylinders and regulators store a lot of energy. Follow the equipment maker's instructions, never exceed a vessel's rated pressure, and keep cylinders upright and away from heat. Bottles that make their own fizz by fermentation, such as kombucha and ginger beer, need a different method: see the kombucha second fermentation calculator.
More fizz calculators
Every tool works in ml and fl oz, grams and ounces, °C and °F, and shows its sources.
Two free tools that come in handy when you shop for fizz gear online.
CleanTempMail
Syrup and soda-maker brands often send a first-order code to an email address. A free temporary inbox, with no sign-up and messages deleted after three days, can catch that one code without the newsletters that follow. Use your real address for the order itself, so the receipt, delivery updates and warranty reach you.
Buying SCOBYs, flip-top bottles or a cheap CO2 regulator from a shop you've never heard of? WebTraceCheck's free DNS and domain lookup shows how long a shop's domain has existed, and its disposable cloud browser opens the link away from your own device. A young domain is one signal to weigh, never proof either way.
For 3.5 volumes, a lively sparkling water, about 21.5 psi (1.48 bar) with the water at 4 °C (39 °F). For a gentler 2.5 volumes, about 11 psi (0.77 bar) at the same temperature. Warmer water needs more: 3.5 volumes at 10 °C (50 °F) takes about 29 psi.
What does "volumes of CO2" mean?
It compares the gas with the drink: 3 volumes means each litre holds 3 litres of CO2, measured at 0 °C and normal air pressure. One volume is about 1.96 g of CO2 per litre, so 3 volumes is about 5.9 g per litre.
Why does cold water need less pressure?
Gases dissolve better in cold liquids. At 4 °C one bar of CO2 dissolves about 1.40 volumes; at 20 °C only about 0.87. So the colder the drink, the less pressure it takes to reach the same fizz, and the better it keeps that fizz once poured.
How long does force carbonation take?
UF/IFAS says a keg fitted with a carbonation stone can be fully carbonated within hours, and that shaking speeds it up a lot. Without a stone or shaking, the gas only enters through the surface, so it takes much longer; we have not found a tested figure for that to quote, so taste it as you go.
Do I need more pressure at high altitude?
Yes, a little. Your gauge reads above the local air pressure, which is lower up high. At about 1,600 m (5,280 ft) that means roughly 2.6 psi more on the gauge for the same fizz. Enter your altitude and the calculator adds it.
Does this work for kombucha, soda or beer?
For force carbonating any of them on a regulator, yes, as a close guide: the equation is for water, and sugar and alcohol make a drink hold slightly less CO2. Drinks that carbonate themselves by fermenting in the bottle need the sugar-based method in the kombucha and ginger beer calculators instead.
Sources
Carbonation levels by drink (Table 1), equilibrium volumes in water (Table 2), 1.96 g/L per volume, 0.6 and 8 volumes, carbonating within hours: Song X, Wendrick N, Sims CA, MacIntosh A. A Guide to Carbonating Beverages at Small Scale, UF/IFAS Extension EDIS FSHN20-34 (published October 2020, revised January 2024).
Still wine at no more than 0.392 g CO2 per 100 ml, hard cider at no more than 0.64 g: 26 U.S.C. § 5041, via Cornell Law School's Legal Information Institute (checked 5 November 2026).