Free tool
Work out exactly how much sugar to add at bottling to carbonate your brew. Enter your batch size, the beer's temperature and a target carbonation level, and it handles the rest.
When you bottle, a small, measured dose of sugar gives the remaining yeast something to ferment. They produce CO₂, and because the bottle is sealed, that CO₂ dissolves into the beer and carbonates it. Too little sugar leaves it flat; too much risks overcarbonation (and, in extremes, bottle bombs), so getting the amount right matters.
The calculation accounts for the CO₂ already dissolved in your beer, which depends on temperature. Warmer beer holds less, so it only adds what's needed to reach your target.
It depends on your target carbonation and beer temperature, but a common rule of thumb is roughly 6-7 g of dextrose per litre for a typical 2.4 volumes of CO₂. The calculator above gives the exact figure for your batch.
Dextrose (corn sugar) and sucrose (table sugar) both work. Table sugar is slightly more concentrated, so you need a little less of it, about 5% less than dextrose for the same carbonation. The calculator adjusts for whichever you choose.
Beer already holds dissolved CO₂, and warmer beer holds less. The calculator uses the highest temperature your beer reached after fermentation to work out the residual CO₂, then adds only what is needed to reach your target.
British ales sit around 1.5-2.0 volumes, most pale ales and lagers around 2.4, wheat beers and Belgian styles 3.0+, and cider around 2.5-3.0. Pick the closest style in the calculator.
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