Force Carbonating Calculator | Step-by-Step Guide

CO2 Forced carbonation calculator

Does trying to force carbonate your homebrew seem intimidating? It really isn’t that difficult.

Many homebrewers achieve that perfect fizz in their beers by force carbonating at home. We’re not talking about some kind of Jedi trick (use the force Luke!), but even for a beginner, it can be done with ease and minimal risk.

When your beer has finished fermenting it’s time to carbonate.

There’s a choice of two carbonation methods for every homebrewer. You can prime in the keg with natural carbonation and wait the required two to three weeks, or try force carbonating your beer in just a few days.

With both methods of carbonation, you will need to determine the volumes of CO2 your chosen beer style needs.

Our force carbonation calculator calculates the required pressure to force carbonate your chosen style of beer to the recommend CO2 volume based on the beer’s temperature in degrees Fahrenheit or Celsius.

About our Force Carbonation Calculator

The force carbonation calculator calculates the desired CO2 volume for your chosen style of beer you are brewing based on the beer’s temperature in degrees Fahrenheit or Celsius.

A drop-down styles menu shows over 20 types of beer accompanied by a recommended CO2 volume. The calculator then uses the beer style to calculate the recommended PSI (or bar) carbonation pressure setting to achieve that level of carbonation.

The Formula Behind the Calculator

T = Temperature (ºF)

V = Desired CO2 Volume

PSI = -16.6999 – 0.0101059*T + 0.00116512*T^2 + 0.173354*T*V + 4.24267*V – 0.0684226*V^2

Celsius to Fahrenheit Conversion

T (ºF) = T (ºC) *1.8 + 32

PSI to Bar Calculation

bar = psi * 0.0689475729


bar = psi / 14.5037738

What is Force Carbonation?

When your beer is ready for packaging, either in a keg or bottles, the process of naturally creating the CO2 needed for the beer’s fizz requires you to feed the leftover yeast additional sugars, or to prime the beer.

Force carbonation allows you to directly infuse CO2 gas into the beer from a CO2 cylinder but only when using a keg. Force carbonation is not suitable for bottle carbonation at home.

Rather than taking a couple of weeks, as bottle-conditioning can take, the force carbonation process can help you reduce the carbonation time and turn around your beer in 12-24 hours.

As well as being much faster, force carbonation will also give more consistent levels of carbonation, removing much of the guesswork of priming with sugar, even when using complicated formulae or sugar calculators.

There are two force carbonation techniques you can choose to add that fizz to your homebrew keg, the main difference between them being the amount of time it takes to force carbonate the beer.

Method one, the traditional force carbonation method, uses lower pressure levels (or psi) and a longer carbonation time.

The second carbonation method is known as the “Shake” method, or the Burst Carbonation technique, and involves a lot more physical effort, some would say akin to a physical workout, but is much faster.

The Equipment Needed for Force Carbonation

Whichever carbonation approach you choose to follow, you will need to have similar supplies at hand. The basic equipment you will need is:

  • Cornelius Keg
  • Regulator
  • Carbon Dioxide
  • An extra fitting for the keg which allows you to push the CO2 through the draw tube.

We always recommend that you should choose homebrew-style kegs that have a ball lock and gas posts. You can find them at most good homebrew shops or from online retailers such as Amazon.

If you want to go a bit more advanced you could use a quick carbonation kit with a durable diffusion or carbonation stone like the Bilchman QuickCarb carbonator which you can also find on Amazon.

What Is a Cornelius Keg?

A corny keg, as they are also known, is a keg that was originally invented by Coca-Cola in the late 50s for use in restaurants to dispense their sodas.

The kegs have since been adapted for beer brewing and allowing homebrewers to carbonate their beer with gas.

A stainless steel upright cylindrical tank, the corny keg has rubber gaskets designed to hold pressurized liquids such as beer to a maximum psi of 130, making them much safer and easier to use than traditional kegs.

Ideal for the newbie Homebrewers who may already be nervous about force carbonating at home.

How Does the Cornelius Keg Work?

The keg has 3 key components which keep the beer under pressure: the lid, a gas side post, and a draught post. A shallow lip on the lid holds the gasket ring to seal in both the air and liquid.

A CO2 line links to the gas side posts on the keg through a gray connector. An O-ring on the post allows the dip tube to make contact with either the gas line disconnect or the keg itself.

Preparation for Both Methods of Force Carbonation

First off, you will need to install a ball lock conversion kit to your existing kegerator lines which will allow you to connect both the liquid and gas lines of the keg to your existing kegerator lines without sacrificing the ability to use standard ball bearing style kegs.

Once the ball lock conversion kit has been installed, you will need to prepare the gas line for attaching to the keg.

Normally, it is the liquid post that dips all the way to the bottom of a Cornelius keg with gas flowing in from the top of the keg to push the liquid from the bottom up the liquid tube when pressure is built up.

With force carbonation, you want to do the opposite and send the CO2 directly to the bottom of the liquid so it rises up through the beer.

To do this, you need to remove the gas socket from the gas line and put it somewhere safe. Next, take the black socket from the liquid line and attached it to the gas line.

The sockets are only designed to attach to the respective gas or liquid posts, so doing this will enable you to attach the gas directly to the liquid post and the tube which goes all the way to the bottom of the keg.

Next, purge the keg by slowly turning the gas cylinder to 5 psi and checking for any leaks on the line, at the liquid post, or around the lid of the keg.

Stop! Before You Start Force Carbonate – The Importance of a Diacetyl Rest

A mistake many homebrewers make is to begin the force carbonation process as soon as they transfer their homebrew from the fermenter to the keg.

Although this often includes lowering the temperature while introducing CO2 into the beer for more efficient carbonation, it doesn’t allow for the Diacetyl (an unwanted byproduct of the fermentation process) to reabsorb into the yeast without the ample time or the correct temperature environment.

We always recommend you leave your beer to rest at room temperature for a couple of days once the final gravity has been reached in order to get rid of that excess Diacetyl.

Carbonating a beer with Diacetyl still present will more likely give the beer off-flavors such as a buttery, almost popcorn-like taste.

Methods of Force Carbonation

Quick Force Carbonate Method

Open the purge valve for about 20 seconds to purge all oxygen from the keg’s head space with CO2. Adjust the screw on the regulator to set it to 30 psi.

You will hear gas bubbling inside the keg. It will continue for a little while and then stop. This is because the keg is standing upright and there is only a small amount of surface area for the CO2 to dissolve into.

If you have switched out the connections and have CO2 going down the beer out line, you will want to shake the keg back and forth while it is still standing so that the CO2 will migrate up through the beer.

As long as you keep shaking and rolling the keg, CO2 will continue to flow and you will hear bubbles in your keg.

When you stop rolling the keg, listen for the bubbles to stop. It is going to take a little while at first, but as you get more CO2 dissolved into the beer, it will take less and less time for the bubbles to stop.

This is telling you that your beer is carbonating.

Shaking or rolling the keg will start the flow of CO2 again. If you let it go long enough, eventually, no matter how much you roll or shake the keg, no more carbon dioxide will go into solution and you won’t hear any more bubbles in the keg.

Your beer is now fully, and probably over-, carbonated.

I generally don’t let it go that far. I normally roll the keg for about 4 minutes.

And when I say I roll it for 4 minutes, I mean I really get after it, keeping the keg rolling vigorously the entire time, stopping for a short time to listen and check how fast the bubbles stop flowing.

It always seems that at around the 4-minute mark, it doesn’t take but a few seconds for the bubbles to stop flowing. This is my indication that it’s time to stop.

Of course, you will have to adjust the time based on how vigorously you roll and shake the keg. The word “vigorously” is relative and will be different for each person.

So, you might want to let it go for 3 or 4 minutes the first time and check the carbonation level in a couple of hours to see if it is to your liking.

It’s best to let the keg set inside your kegerator or your chest freezer for a few hours to settle down before you try to dispense it. Patience, young homebrewer!

Once it’s carbonated, set the keg back in the kegerator, set the pressure according to the calculator and the temperature inside the kegerator or cooler, and forget it for a while.

The CO2 inside the beer will equalize with the pressure set on your regulator. If you find you have over-carbonated your beer, lower the pressure on the regulator and pull the pressure relief valve.

The CO2 will come out of solution to re-pressurize the head space. By releasing the pressure frequently, the beer will lose carbonation and will equalize to the correct pressure you set on the regulator.

If you under-carbonated the beer, more will go into solution until it is equalized with the pressure you set on the regulator as per the chart (or if you are still in a hurry, repeat the process of purging the head space, putting 25-30 psi on the regulator and agitate the keg for a few more minutes…let it settle a couple of hours and check it again).

Check Your Gas Line for Beer

Make sure you have a check valve in your gas line, otherwise beer can get into the line and regulator and ruin it.

Just to be safe, I usually disconnect the gas line from the keg, hold the quick connect against the towel, and depress the pin inside the quick connect with a long slender object like a pen.

All the beer in the line will shoot into the towel. Keep depressing the pin until the gas line is purged of beer.

The Slow Force Carbonate Method

Another way to force carbonate your beer is to use the force carbonation calculator to find the correct pressure you need for the amount of carbonation you want at the temperature inside your cooler.

Just keep the keg in the kegerator or fridge, set the pressure, and forget it.

The CO2 will go into solution over the course of a few days. This is the easy way to force carbonate your beer, but it does take some time.

If you shake or roll the keg every once in a while it will happen quicker.

When using this method, spray a little soapy water around all the connections and the lid to make sure you don’t have a leak. If you detect a leak, fix the problem before reapplying pressure.

Once you lose an entire tank of CO2 in a day, you’ll know why this is important.

Once you have your beer carbonated, you will need a counter-pressure bottle filler to bottle the carbonated beer for competitions.

Hgkeke Counter Pressure Bottle Filler Stainless Steel Bottle Filler Counter Pressure Beer Bottling Wand 60psi CO2 Gauge 1/4 & 5/16 Barb Homebrew Beer Bottle Filler Hand Held Bottle Filler 3ft Hose
  • SOLID STAINLESS STEEL BODY & NO LEAK NO MESS: Food grade 304 stainless steel counter-pressure bottle filler with a three-way valve to control the co2 & beer with one hand. Seamless connections with Teflon tape to ensure 100% no leaks! Upgraded 1/4" and 5/16” barbs are more compatible with most gas/ liquid tubes. Well crafted, easy to fit with tubes, no scratch.
  • INSTANT PRESSURE GAUGE, NO MORE REPEATING TEST: Pressure gauge accurately shows the pressure in the bottle enables better control of filling. No more guessing, waiting, repeating the pressure test. Time saver! Pressure in the bottle should be 3-5 psi lower than the pressure in the keg. The bleed valve can adjust the pressure in the bottle, reduce/ release beer foams.
  • NO CARBONATION LOSS & MOST USED FOR BEER BOTTLING: 6.6” Filling Tube with 3# silicone stopper for oxygen-free beer bottling. Stopper prevents air into the bottle during bottling, no carbonation will lose. The bottle’s height should be taller than 6.6” (the filling tube), the bottle lip's I.D. should be 0.73 to 0.86 inch(fit with 3# stopper). The stopper can be replaced with your other size stoppers if necessary.

Note: If you plan on lowering the temperature of your keg, from 42°F say down to 34°F before you force carbonate your homebrew, add a few extra pounds of pressure first.

The gas in the head space of your keg will dissolve quickly as the temperature drops and if the O-ring on your lid is not seated properly, it could leak.

When you reach your desired temperature, the gas will come out of solution and escape out of the leaky O-ring, leaving your beer with no carbonation.

It is always a good idea to give a quick spray of soapy water on all the keg fittings and connections to make sure there are no leaks (wait till you open your kegerator one day to find two inches of beer in the bottom).

Blichmann Engineering QuickCarb Keg Carbonator

 Blichmann QuickCarb Beer Carbonato

No one likes waiting, and the QuickCarb is the way to eliminate the wait from carbonating your homebrew.

This high-pressure CO2-injection system from Blichmann Engineering™ will carbonate a keg in 30 minutes, with no chance of over-carbonating your beer.

All connectors are included, and the unit hangs from the front of your keg.

Use is simple:

Just sanitize the unit using the built-in pump, and connect hoses to your Keg and CO2 system.

Turn on the gas, plug in the unit, and 30-40 minutes later, your beer will be perfectly carbonated.

Cleanup is just as easy, as you can run cleaner and sanitizer through the system using the pump as well.

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