Calculating the amount of priming sugar needed to bottle carbonate hard cider can be a tricky and intimidating process for the first timer. When bottle carbonating cider, there are many factors to take into consideration and once you put the cap on the bottle, you are stuck with the result.
A priming sugar calculator can take a lot of the guesswork out of carbonating and make it a lot safer. Also, an inexpensive digital scale that is accurate to .01 gram will take the guesswork out of measuring. Measuring in fractions of a tablespoon can get challenging!
To calculate the amount of priming sugar needed to carbonate cider you will need to know:
- The volumes of CO2 you would like in your cider
- The temperature of the cider at the time of bottling
- The volume of cider you will be bottling
The old rule of thumb I learned, one ounce of sugar per gallon, may be close but it doesn’t account for temperature which is directly related to the CO2 still dissolved in the cider from fermentation.
CO2 is one of the byproducts of fermentation and depending on the temperature of your hard cider some quantity will be present at the time of bottling. When cider is fermented at colder temperatures, more CO2 will be dissolved in the cider before bottling.
You may have noticed what appears to be carbonation when taking a final gravity reading. This is CO2 that is dissolved in the cider from the fermentation process. This CO2 must be taken into consideration when calculating the amount of priming sugar required to carbonate cider. If you bottle your cider while it is cold (after a cold crash for instance) and do not account for existing CO2, you could over carbonate the cider or cause the bottles to burst.
On the other side, when the cider is warmer, it releases CO2 and will be less likely to naturally hold on to it. If you were to use the rule of thumb for warm cider, chances are you would end up under carbonated.
What is a ‘volume of CO2’?
A volume of CO2 is the measurement used to quantify the amount of carbon dioxide dissolved in a liquid, or in our case, cider.
One volume of CO2 is equal to the volume it would take up if it was taken out of a solution released to standard temperature (32F) and atmospheric pressure (1 Atmosphere).
So, if you have 2 volumes of CO2 in 1 gallon of cider you have two gallons of CO2 dissolved in the cider. If you were to release this CO2 and capture it in a vessel, you would be able to fill two gallons worth of volume with the CO2 under standard temperature and pressure.
Examples of ‘volumes of CO2’ per style of beer:
|British Style Ales||1.5 – 2.0 volumes|
|Belgian Ales||1.9 – 2.4 volumes|
|American Ales and Lager||2.2 – 2.7 volumes|
|Fruit Lambic||3.0 – 4.5 volumes|
|Porter, Stout||1.7 – 2.3 volumes|
|European Lagers||2.2 – 2.7 volumes|
|Lambic||2.4 – 2.8 volumes|
|German Wheat Beer||3.3 – 4.5 volumes|
Priming Sugar Equation
- PS= Dextrose required in grams
- VC= Volume of cider
- CD= Colume of carbon dioxide
- T= Cider temperture before bottling
PS = 15.195 * VC (CD – 3.0378) + ((5.0062*10^-2) * T) – (2.6555 x 10^-4 * (T^2))
source: Brew By The Numbers, Michael L. Hall, Ph.D.1995
Dextrose in grams required to prime cider for carbonation.
|Volumes of CO2|
Carbonating hard cider with other sugar sources
This calculator is only for priming cider with dextrose which is corn sugar. If you choose to prime your bottles with another sugar source such as apple juice concentrate, honey or even white sugar, you will need to calculate the adjustments. Not all sugar sources are 100% fermentable or can be measured in the same way.
Make sure your cider is fully fermented
It’s also important to note that if your cider has not finished fermenting than these calculations will not be accurate. Any fermentable sugars that are already present will continue to ferment along with the priming sugar and produce unknown and potentially dangerous results.
Only bottle a cider that has fully completed fermentation. Take separate hydrometer readings two days apart to verify that the final gravity is no longer changing. This is an indicator that fermentation has stopped. Please note that cooler temperatures can cause very slow fermentation that appears to be complete. Do not rely on airlock activity for indicating completion.
Failing to properly calculate and measure the priming sugar when bottling hard cider can result in over pressurized bottles. This can cause the bottles to explode or the caps to unexpectedly and forcefully blow off. This calculator is based on an equation from a qualified source but should be used at your own risk. Double check calculations and measurements before priming and bottling your hard cider. Please be responsible – Home Cider Making.