🫧 Priming Sugar Calculator
Enter your batch volume, target carbonation level, and highest fermentation temperature to calculate the amount of corn sugar (dextrose) needed for bottle conditioning.
How the sugar dose is worked out
Beer already holds dissolved CO2 left over from fermentation, and how much depends on the warmest temperature it reached. The page estimates that residual, subtracts it from your target, and doses 4 grams of corn sugar per litre for each remaining volume:
residual vols = 3.0378 - 0.050062T + 0.00026555T² (T in °F)
litres = gallons × 3.78541
corn sugar g = 4 × litres × (target vols - residual vols)With the defaults — 5 gallons, 2.4 volumes, 68 °F — the residual is 0.86 volumes, so 1.54 must come from sugar: 4 × 18.93 × 1.54 = 116.5 g, or 4.11 oz. Ferment at 75 °F and the residual drops to 0.78, pushing the dose to 123 g.
Targets and substitutions
| Style | Volumes CO2 | Corn sugar, 5 gal at 68 °F |
|---|---|---|
| British ale, cask-ish | 2.0 | 86 g |
| American ale, porter | 2.4 | 117 g |
| Lager, saison | 2.8 | 147 g |
| Hefeweizen | 3.5 | 200 g |
The figure is dextrose. Table sugar carries slightly more fermentable weight, so use about 91% of it; dry malt extract about 133%. Enter the highest temperature the beer saw after fermentation finished, not the pitching temperature. If that residual already exceeds your target the page says so rather than returning a negative dose.
Frequently asked questions
How much priming sugar for 5 gallons?
About 117 g (4.1 oz) of corn sugar for 2.4 volumes on beer that peaked at 68 °F. Boil it in a cup of water, cool it, and stir it into the bottling bucket rather than into each bottle.
Can I use table sugar instead of corn sugar?
Yes. Sucrose ferments out completely and yields a little more CO2 per gram, so multiply the answer by about 0.91 — 117 g of dextrose becomes about 106 g of table sugar. No flavour difference at this dose.
Why does it ask for fermentation temperature?
Because CO2 is less soluble when warm. Beer that finished at 60 °F retains 0.99 volumes and needs only 107 g of sugar; at 80 °F it holds 0.73 and needs 126 g for the same result.