Priming sugar calculator
Enter the volume of beer you will bottle, the highest temperature it reached after fermentation and the carbonation you want in volumes of CO₂. The calculator subtracts the CO₂ already dissolved in the beer and gives the sugar to add, in grams and ounces.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose litres and °C or US gallons and °F.
- Enter the volume of beer you will actually bottle (after leaving the sediment behind).
- Enter the highest temperature the beer reached after fermentation, not the bottling-day temperature if it was warmer before.
- Set the target CO₂ volumes and the sugar you use.
- Residual CO₂ = 3.0378 − 0.050062·T + 0.00026555·T², with T in °F.
- Table sugar (g) = 15.195 × gallons × (target − residual).
- Corn sugar = table sugar ÷ 0.91; dry malt extract = table sugar ÷ 0.68.
Worked example
5 gallons at 68 °F, 2.4 volumes, table sugar:
- residual CO₂ = 3.0378 − 3.4042 + 1.2279 = 0.86 volumes;
- CO₂ to add = 2.4 − 0.86 = 1.54 volumes;
- sugar = 15.195 × 5 × 1.54 = 117 g (4.12 oz), 6.18 g per litre.
The same beer in metric, 20 L at 20 °C: 124 g of table sugar.
Common mistakes
- Using the volume in the fermenter instead of the volume bottled: the sediment and dead space stay behind.
- Using a cold bottling temperature for an ale that fermented warm: that overstates the residual CO₂ and under-carbonates.
- Bottling before fermentation is finished: the remaining sugar adds to the priming sugar and can over-carbonate. Check that the gravity has been stable for a few days.
Frequently asked questions
How much corn sugar do I need for 5 gallons?
For 5 US gallons fermented at 68 °F and a target of 2.4 volumes, table sugar is 117 g (4.12 oz) and corn sugar 117 ÷ 0.91 = 128 g (4.53 oz). The often-quoted ¾ cup of corn sugar for 5 gallons is a rough average; the right amount depends on temperature and style.
Why does temperature matter?
Cooler beer keeps more CO₂ from fermentation dissolved. The residual CO₂ is estimated from the highest temperature the beer reached after primary fermentation, with 3.0378 − 0.050062·T + 0.00026555·T² (T in °F). At 68 °F that is 0.86 volumes; at 50 °F it is 1.2, so a lager needs less sugar than an ale.
What carbonation level should I choose?
Roughly: British ales 1.5–2.2 volumes, most American ales and lagers 2.2–2.7, Belgian ales and wheat beers 2.7–3.5 or more. Do not go above what your bottles are rated for; ordinary beer bottles are not meant for very high carbonation.
How do the sugars compare?
The tool takes table sugar (sucrose) as the reference: 15.195 g per US gallon for each volume of CO₂. Corn sugar is used at table sugar ÷ 0.91, because dextrose monohydrate contains water and gives less CO₂ per gram, and dry malt extract at table sugar ÷ 0.68, because only part of it ferments.
How do I add the sugar?
Dissolve it in a little boiling water, cool, pour it into the bottling bucket and rack the beer onto it so it mixes evenly. Keep the bottles at room temperature for about two weeks before chilling them.