---
title: "Volumes of CO2, Explained: What Your Carbonation Number Actually Means"
url: https://fizzwizz.ca/volumes-of-co2-explained/
date: 2026-10-15T07:41:38+00:00
modified: 2026-10-15T07:41:38+00:00
lang: en_US
---

# Volumes of CO2, Explained: What Your Carbonation Number Actually Means

Every FizzWizz run starts with one number: the carbonation level you want, in volumes of CO2. This post explains what that number means, why temperature and pressure decide it, and where to start for different drinks.

## What a "volume" is

One volume of CO2 means the beverage holds as much CO2 as its own volume of the gas would take up at standard temperature and pressure. A litre of beer at 2.5 volumes holds 2.5 litres of CO2 (measured at standard conditions) dissolved in it.

You'll also see carbonation given in grams per litre. The conversion is close to 2: one volume is about 1.96 g/L ([University of Florida IFAS](https://ask.ifas.ufl.edu/publication/FS379)).

## Temperature and pressure set the level

![Two beakers of carbonated liquid at 0°C and 10°C, the colder one holding visibly more bubbles.](https://fizzwizz.ca/wp-content/uploads/2026/10/01-inline-cold-vs-warm-1024x756.jpg)

CO2 dissolves according to Henry's law: at a given temperature, the amount dissolved is proportional to the partial pressure of CO2 above the liquid ([Oxford Companion to Beer](https://www.beerandbrewing.com/dictionary/kwchv8B8mS)). Colder liquid holds more CO2 at the same pressure.

That means there is one equilibrium pressure for any combination of temperature and target volumes. For water, published values look like this ([University of Florida IFAS](https://ask.ifas.ufl.edu/publication/FS379), calculated for water):

| Pressure (psig) | 0°C | 5°C | 10°C | 15°C |
| --- | --- | --- | --- | --- |
| 5 | 2.15 vol | 1.83 vol | 1.57 vol | 1.36 vol |
| 10 | 2.69 vol | 2.30 vol | 1.97 vol | 1.70 vol |
| 15 | 3.24 vol | 2.76 vol | 2.37 vol | 2.05 vol |
| 20 | 3.78 vol | 3.23 vol | 2.77 vol | 2.39 vol |

Two things jump out. At 10 psig, the same tank holds about 0.4 volumes less at 5°C than at 0°C. And sugar and alcohol shift these numbers, so treat any table as a starting point for your own product.

## Why FizzWizz recalculates constantly

Because the equilibrium pressure depends on temperature, a fixed pressure only gives the right result if the temperature never moves. In a real bright tank it does move. On the run in [Anatomy of a Perfect Carbonation Plot](/perfect-carbonation-plot/), the product drifted by nearly 1.5°C overnight.

FizzWizz reads product temperature and tank pressure, calculates the finish pressure for your target at that temperature, adds CO2 through the stone until the tank gets there, and keeps recalculating as conditions change. You set volumes; it handles the pressure.

## Typical targets

Published ranges for common drinks ([University of Florida IFAS](https://ask.ifas.ufl.edu/publication/FS379)):

| Drink | Volumes of CO2 |
| --- | --- |
| Champagne | 4.6 to 6 |
| German wheat beer | about 5 |
| High-carbonation soda (cola) | 3.5 to 4 |
| Club soda and tonic | 2.5 to 3.5 |
| Lemon-lime soda | 2.5 to 3.5 |
| Typical lager | 2.4 to 2.6 |
| British ales | 1.5 to 2.2 |

The same source puts the minimum people can detect at about 0.6 volumes.

FizzWizz defaults to 2.4 volumes in carbonation mode, and you can change the target to suit your product.

## Getting the number right in practice

- **Trust the temperature reading.** FizzWizz calculates from it, so a probe that reads warm leaves the product under-carbonated. See [the ice-water test](/ice-water-test/).
- **Start from a known baseline.** If the tank already holds pressure from something other than CO2, the reading misleads the controller. See [When Your Carbonation Plot Starts Too High](/high-starting-pressure/).
- **Measure the result.** Check finished product with a carbonation meter rather than by taste. See [Mouthfeel Isn't a Measurement](/mouthfeel-isnt-a-measurement/).

BrewWizz's free calculation tools in the web app will run these numbers for your product.

**Not sure what target suits your product?** [Contact us](/contact/).

## Sources

- University of Florida IFAS, [A Guide to Carbonating Beverages at Small Scale (FS379)](https://ask.ifas.ufl.edu/publication/FS379): unit conversion, Table 1 (targets), Table 2 (equilibrium values for water).
- Oxford Companion to Beer, [Henry's law](https://www.beerandbrewing.com/dictionary/kwchv8B8mS).
- FizzWizz [How It Works](/how-it-works/) (calculation steps) and [What's Happening in Your Tank](/bubble-size-physics/) (2.4 volume default).