---
title: "Carbonation Calculator: CO2 Volumes & PSI | Blue Fizz Club"
description: "What psi to carbonate water? Enter the temperature and the CO2 volumes you want for the regulator pressure in psi and bar, with a chart from 0 to 25 °C."
url: https://bluefizzclub.me/
---

Henry's law, checked against a university table

# 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.

## 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:

volumes = 0.034 × exp[2400 × (1/T − 1/298.15)] × p × 22.414

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

1. 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.
2. Purge the air from the headspace with CO2: air in the headspace takes up pressure without adding fizz.
3. 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.
4. 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](https://highnestle.top/).

## 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](https://bluefizzclub.me/kombucha-second-fermentation/).

## More fizz calculators

Every tool works in ml and fl oz, grams and ounces, °C and °F, and shows its sources.

- [Soda syrup calculator](https://bluefizzclub.me/homemade-soda-syrup-calculator/): Syrup ratio, citric acid and how much per glass, with sugar per serving against NHS, WHO and US guidance.
- [Kombucha second fermentation](https://bluefizzclub.me/kombucha-second-fermentation/): Sugar or juice per bottle, the pressure it can build, and a squeeze-test schedule.
- [Ginger beer calculator](https://bluefizzclub.me/ginger-beer-calculator/): Ginger, sugar, lemon and yeast or ginger bug for any batch, with the plastic-bottle test.
- [Soda maker cost per litre](https://bluefizzclub.me/sparkling-water-maker-cost/): Gas, flavour and bottled prices to cost per litre, break-even date and bottles saved.
- [Alcohol-free party drinks](https://bluefizzclub.me/alcohol-free-drinks/): A fizz-bar planner for any party size, original recipes and a printable menu card.

## Recommended

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.

[Open a temporary inbox](https://cleantempmail.com/)

### WebTraceCheck

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.

[Try the cloud browser](https://webtracecheck.com/)

## Questions

**What psi should I carbonate water at?**

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](https://edis.ifas.ufl.edu/publication/FS379), UF/IFAS Extension EDIS FSHN20-34 (published October 2020, revised January 2024).
- Henry's-law constants for CO2 in water, 0.034 mol/(kg·bar) and 2400 K: [NIST Chemistry WebBook, Carbon dioxide, Henry's Law data](https://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Mask=10) (checked 5 November 2026).
- Molar volume of an ideal gas at 273.15 K and 101.325 kPa, 22.413 969 L/mol: [NIST, CODATA 2022 recommended values](https://physics.nist.gov/cgi-bin/cuu/Value?mvolstd) (checked 5 November 2026).
- Air pressure by altitude: [NASA Glenn Research Center, Earth Atmosphere Model (metric units)](https://www.grc.nasa.gov/www/k-12/airplane/atmosmet.html) (checked 5 November 2026).
- 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](https://www.law.cornell.edu/uscode/text/26/5041), via Cornell Law School's Legal Information Institute (checked 5 November 2026).
- psi, bar, °C and °F conversions: [NIST Guide to the SI (SP 811), Appendix B.8](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8).