Priming Sugar Calculator
Priming sugar grams for bottle carbonation from batch size, temp, and target volumes.
What it does
Bottle carbonation adds the CO2 that fermentation left out: the beer already holds gas from its warmest days, and priming sugar ferments into the rest inside the sealed bottle. Guess the sugar and bottles gush or burst; weigh it and they pour clean.
The tool above takes batch size, warmest temperature, target volumes, and sugar type. It returns weighed grams with ounces and the residual already in the beer.
The default 5 gallons at 68 F to 2.4 volumes needs 143.8 g dextrose (5.1 oz) over a 0.85 residual. The metric mirror of 18.93 liters at 20 C reads the same.
Math follows American Homebrewers Association practice with University of Florida extension tables behind it. Both anchor the 1.96 g per liter volume and the 0.46 sugar yield used here.
How to use
- Pick gallons or liters for the batch.
- Enter batch size at bottling.
- Enter the warmest post fermentation temp.
- Enter target volumes for the style.
- Pick dextrose or sucrose.
- Weigh the grams shown, dissolve, mix gently.
Formula
- target
- Style target CO2 volumes, often 2.4 to 2.6.
- residual
- CO2 already dissolved, from peak temp.
- liters
- Batch size in liters.
- 0.46
- Sugar yield factor, 0.46 g CO2 per g.
One volume equals 1.96 g CO2 per liter, and each gram of sugar yields about 0.46 g CO2. Residual comes from the warmest post fermentation temperature by linear interpolation of the table below. Cold crashed readings never raise residual.
Worked example
Example: 5 gallons to 2.4 volumes
Imperial defaults: 5 gal, 68 F peak temp, 2.4 volumes, dextrose.
- Batch: 5 gal = 18.927 liters.
- Residual at 68 F: 0.85 volumes.
- To add: 2.4 - 0.85 = 1.55 volumes.
- CO2: 1.55 x 1.96 x 18.927 = 57.5 g.
- Sucrose: 57.5 / 0.46 = 125 g.
- Dextrose: 125 x 1.15 = 143.8 g (5.1 oz).
- Tool shows 143.8 g dextrose, 5.1 oz, 0.85 vol in beer.
Reference table
| Temp | Residual | Note |
|---|---|---|
| 0 C (32 F) | 1.60 vol | Cold stored beer |
| 5 C (41 F) | 1.37 vol | Lager range |
| 10 C (50 F) | 1.17 vol | Cellar range |
| 15 C (59 F) | 1.01 vol | Cool ale range |
| 20 C (68 F) | About 0.85 vol | Typical ale, interpolated |
Limits
- Estimates; yeast health and headspace shift results.
- Capped near 3 volumes for standard bottles.
- Honey and malt need their own factors.
- Stalled yeast never carbonates on schedule.
Common mistakes
- Measuring sugar in cups.
- Using current cold crash temp.
- Boiling the sugar into caramel.
- Splashing oxygen while mixing.
- Capping non pressure rated bottles.
Try it yourself
Quick checks. Answers sit tucked under each question.
Default batch with table sugar?
Same 1.55 volumes need 125 g sucrose (4.4 oz).
Default batch to 2.6 volumes?
Add 1.75 volumes: 64.9 g CO2, 162.3 g dextrose (5.7 oz).
1 gallon at 68 F to 2.4 volumes?
CO2 11.5 g, sucrose 25 g, dextrose 28.8 g.
Questions
Cups or scale for priming sugar?
Weigh it. Cup weights swing with grain size and packing, and the 3/4 cup rule overcarbonates many styles.
Which temperature sets residual CO2?
The warmest point during or after fermentation. Cold crashing never restores driven off gas.
How much more dextrose than table sugar?
About 10 to 16% more than sucrose. The tool uses 1.15x for dextrose monohydrate.
How long does bottle conditioning take?
Hold bottles at 68 to 80 F for 2 to 4 weeks, then test weekly.
Can I prime with honey or malt?
Yes, but it needs more weight and more time than corn sugar, and mixing must stay gentle.
When do bottles burst?
Use pressure rated bottles and cap styles near 3 volumes. Above that, keg instead.