Priming Sugar Calculator

How it works

This priming sugar calculator (sometimes searched for as a bottle carbonation calculator) works out how many grams of sugar to add at bottling so your beer naturally carbonates to a chosen CO2 level. The key thing most beer priming sugar chart tables skip is that your beer already holds some dissolved CO2 from fermentation — you only need to add enough sugar to top that up to your target, not to reach it from zero.

The residual CO2 already in solution depends on the warmest temperature the beer reached during fermentation, following the standard priming-calculator approximation used by Brewer’s Friend’s priming sugar calculator:

Fermentation temp (°F) = Fermentation temp (°C) × 9/5 + 32
Residual CO2 (volumes) = 3.0378 − 0.050062 × TempF + 0.00026555 × TempF²
CO2 needed = Target CO2 volumes − Residual CO2 (never below 0)

From there, working out how much priming sugar to add follows a simple relationship: roughly 4 grams of fermentable sugar per litre of beer, per volume of CO2 needed, scaled by a fermentability factor for whichever sugar you’re using. Dextrose (corn sugar) is the baseline at a factor of 1.0, table sugar (sucrose) is slightly more fermentable at 0.91, and dry malt extract is less concentrated at 1.33, per the same Brewer’s Friend reference:

Priming sugar (g) = CO2 needed × Batch volume (L) × 4.0 × Sugar type factor
Sugar per litre (g/L) = Priming sugar (g) ÷ Batch volume (L)

Different beer styles target different carbonation levels — a soft British ale sits around 1.9 volumes of CO2, while a fizzy wheat beer can run as high as 3.6. Picking the right style preset (or entering your own target) is what determines how much priming sugar you actually need to add, rather than guessing from a generic chart.

Worked example

Jarrah, a home brewer in Fremantle, Western Australia, has just finished fermenting a 20L batch of American pale ale. His fermentation fridge held the beer at a peak of 20°C during the vigorous first few days, and he wants to bottle-condition it to American ale strength — 2.4 volumes of CO2.

Converting 20°C to Fahrenheit gives 68°F. Plugging that into the residual CO2 formula gives about 0.86 volumes already dissolved in the beer, so Jarrah only needs to add enough sugar for the remaining 1.54 volumes. Using dextrose (factor 1.0), that works out to roughly 123.1g of priming sugar for the whole batch — about 6.15g per litre.

Jarrah has both dextrose and a bag of ordinary table sugar in the pantry, so he compares what each would take for the same batch:

Sugar type	Grams needed
Dextrose / corn sugar	123.1g
Table sugar	112.0g
Dry malt extract	163.7g

He weighs out 123.1g of dextrose on his kitchen scale, dissolves it in a small amount of boiled water, and gently stirs it through the batch before bottling — confident the beer will carbonate to the fizziness he’s after without over-pressurising his stubbies.