Priming Sugar Calculator
Corn sugar, table sugar or another sugar for bottle carbonation, from the CO₂ already in the beer (Henry’s law) and fermentation chemistry.
The priming sugar in grams, ounces and grams per litre, the CO₂ the beer already holds from fermentation, and the CO₂ the sugar must add — for the carbonation you choose, in volumes.
Example: 5 gal to 2.4 volumes after fermenting at 68 °F: 0.88 volumes are already there, so 128 g (4.5 oz) of corn sugar; 20 L to 2.7 volumes after 18 °C takes 136 g of table sugar.
Top up the CO₂
already there.
What a volume of CO₂ is, how much the beer already holds, how much CO₂ a gram of sugar makes, and why bottles set the limit.
Volumes of CO₂
Carbonation is measured in volumes: litres of CO₂, counted at 0 °C and 1 atm, dissolved in each litre of beer. A litre of CO₂ at those conditions weighs 1.977 g. Choose the volumes for the style you are brewing.
What is already there
Beer leaves the fermenter saturated with CO₂ at 1 atm at the warmest temperature it reached after fermentation. By Henry’s law, with the NIST Chemistry WebBook’s constants for CO₂ in water (0.034 mol/(kg·bar) at 25 °C, temperature factor 2400 K), that is about 0.88 volumes at 68 °F. Only the difference needs sugar.
Sugar to CO₂
Yeast turns a molecule of sucrose into four of CO₂ and one of glucose into two, so a gram of table sugar yields 0.514 g of CO₂ and a gram of corn sugar (dextrose monohydrate) 0.444 g, from IUPAC molar masses. For other sugars enter how fermentable they are relative to table sugar.
Bottles have a limit
Glass bottles are made for a pressure. Weigh the sugar rather than measuring by volume, mix it evenly, bottle only fully fermented beer, and keep the carbonation within what your bottles are rated for — over-primed bottles can burst. Inputs stay in your browser; the same anonymous usage counts as the rest of the site apply.
SOURCES
- NIST Chemistry WebBook — Henry’s law data for carbon dioxide
- IUPAC standard atomic weights — molar masses of sucrose, glucose monohydrate and CO₂
Last reviewed 24 September 2026. How results are checked: How we verify.