Priming sugar calculator
Enter your batch size, the warmest temperature the beer reached and your CO₂ target to get how much priming sugar to add, in total and per bottle. Kegging instead? The second tab gives you the regulator pressure for force carbonation.
Target
1 vol = 1.96 g/L. English recipes use vol, German ones g/L.
Beer and bottles
Warmest point at or after the end of fermentation (e.g. diacetyl rest), not the bottling-day temperature.
Priming sugar for the batch
4.4 oz
- Per bottle · 53 bottles of 355 ml (12 oz)
- 2.3 g
- CO₂ from the sugar
- 1.54 vol
- Already in the beer
- 0.86 vol
Runs in your browser. Nothing you enter is sent or stored.
How much priming sugar: the calculation
Your beer is not flat when you bottle it. CO₂ from fermentation is still dissolved in it, and how much depends on temperature: cold beer holds more. The calculator first works out this residual CO₂, then subtracts it from your target. Only the difference has to come from priming sugar.
That difference is multiplied by the batch size and a sugar factor: the grams of that sugar it takes to add one volume of CO₂ to one liter of beer. For 5 gallons at 68 °F and a target of 2.4 volumes, that comes to about 4.4 oz (125 g) of corn sugar.
The temperature is the part people get wrong. Enter the warmest temperature the beer reached at or after the end of fermentation, including a diacetyl rest, not the temperature on bottling day. The CO₂ the beer lost while it was warm does not come back when you cold crash. The same 5 gallons fermented at 50 °F need only 3.5 oz (98 g).
S = (V − Vres) × L × f
Vres = 3.0378 − 0.050062 × T + 0.00026555 × T²
- S
- Priming sugar in grams
- V
- Target CO₂ in volumes
- Vres
- CO₂ already in the beer
- L
- Beer volume in liters
- f
- Sugar factor (g per liter per volume)
- T
- Highest beer temperature in °F
| Temperature | Volumes | g/L |
|---|---|---|
| 32 °F (0 °C) | 1.71 vol | 3.35 g/L |
| 41 °F (5 °C) | 1.43 vol | 2.81 g/L |
| 50 °F (10 °C) | 1.20 vol | 2.35 g/L |
| 59 °F (15 °C) | 1.01 vol | 1.98 g/L |
| 68 °F (20 °C) | 0.86 vol | 1.69 g/L |
| 77 °F (25 °C) | 0.76 vol | 1.48 g/L |
CO₂ volumes by style, and volumes vs. g/L
Carbonation is given in volumes in most English-language recipes: 2.5 volumes means the beer holds 2.5 times its own volume of CO₂ gas. German and many European brewers use grams per liter instead. BrewForge converts with 1 vol = 1.96 g/L, so 2.5 volumes is about 4.9 g/L. Switch between vol and g/L next to the target field and the value converts.
Pick a style in the calculator and it fills in a typical target. British ales sit low, around 1.5 to 2 volumes, while most lagers and American ales land between 2.2 and 2.8. Belgian ales and German wheat beers go higher, which matters for your bottles: see the safety notes below.
| Style | Volumes | g/L |
|---|---|---|
| English bitter | 1.0–2.0 | 2.0–3.9 |
| Stout | 1.8–2.5 | 3.5–4.9 |
| American IPA | 2.2–2.7 | 4.3–5.3 |
| Pilsner | 2.4–2.8 | 4.7–5.5 |
| American lager | 2.5–2.8 | 4.9–5.5 |
| Belgian tripel | 2.4–3.0 | 4.7–5.9 |
| Saison | 2.5–3.5 | 4.9–6.9 |
| Hefeweizen | 2.7–3.6 | 5.3–7.1 |
Force carbonation: keg pressure vs. temperature
In a keg you skip the sugar and let CO₂ from the tank dissolve into the beer under pressure. How much dissolves depends on two things: the pressure on the regulator and the temperature of the beer. Colder beer takes up CO₂ more easily, so it needs less pressure for the same carbonation.
The Force Carbonation tab uses the standard carbonation chart formula and gives the regulator pressure in psi and bar, plus a chart from 32 to 56 °F for your target that includes your own temperature. At 38 °F, 2.4 volumes needs about 10 psi.
- The pressure is what the regulator gauge shows, not absolute pressure.
- Use the temperature of the beer itself, and let the keg chill before you start.
- At serving pressure the beer reaches its target in about a week. Burst carbonating at higher pressure is faster, but easy to overshoot.
- Once carbonated, leave the regulator at the same pressure so the beer stays where it is.
P = −16.6999 − 0.0101059·T + 0.00116512·T² + 0.173354·T·V + 4.24267·V − 0.0684226·V²
bar = psi × 0.0689
- P
- Regulator pressure in psi (gauge)
- T
- Beer temperature in °F
- V
- Target CO₂ in volumes
| Temperature | 2.2 vol | 2.5 vol | 2.8 vol |
|---|---|---|---|
| 32 °F (0 °C) | 5.4 psi | 8.2 psi | 11.0 psi |
| 36 °F (2 °C) | 7.0 psi | 10.0 psi | 13.0 psi |
| 39 °F (4 °C) | 8.6 psi | 11.9 psi | 15.1 psi |
| 43 °F (6 °C) | 10.3 psi | 13.7 psi | 17.1 psi |
| 46 °F (8 °C) | 12.0 psi | 15.6 psi | 19.2 psi |
| 50 °F (10 °C) | 13.8 psi | 17.6 psi | 21.3 psi |
| 54 °F (12 °C) | 15.6 psi | 19.5 psi | 23.5 psi |
Sugar types and bottle safety
Every sugar gives a different amount of CO₂ per gram. Table sugar is almost pure sucrose and ferments completely, so it needs the least. Corn sugar (dextrose) sold for brewing contains water, so you need about 7% more. Honey is about 18% water, and the exact amount varies. Dry malt extract needs about a third more than table sugar because only part of it ferments.
Too much sugar, or sugar added to beer that is still fermenting, builds pressure the bottle cannot hold. These habits keep your bottles in one piece:
- Bottle only finished beer: the gravity should stay the same for two or three days.
- Weigh the sugar. Cups and spoons are too imprecise for this.
- Dissolve the sugar in a little boiled water and stir it gently into the whole batch, so every bottle gets the same amount.
- Standard beer bottles are fine for normal carbonation. Above about 3 volumes, use heavier bottles made for it.
- Keep the bottles at room temperature for two to three weeks, then chill them.
| Sugar | Per L and vol |
|---|---|
| Table sugar (sucrose) | 3.82 g |
| Corn sugar (dextrose) | 4.3 g |
| Honey | 4.9 g |
| Dry malt extract | 5.33 g |
Built into every BrewForge recipe
In BrewForge carbonation is part of the brew. The target comes from your recipe’s style, the beer volume from your brew’s packaged volume, and the beer temperature from the warmest reading your fermentation log recorded. Choose priming sugar or force carbonation, and the sugar amount or regulator pressure is saved with the brew.
- CO₂ target and style range from your recipe
- Peak fermentation temperature from your readings
- Priming or keg plan saved with the brew
Use this calculator via API
The same calculation is also a free JSON API: no account, no key, one GET request. Handy for scripts, spreadsheets and AI assistants that should use exact brewing math instead of estimating it.
Add units=imperial (or one unit parameter per value) for °F, gallons and pounds. Every answer lists the inputs, the units and the formula it used.
GET https://brewforge.sh/api/public/calc/priming-sugar?volume=20&beerTemp=20&co2=2.4
GET https://brewforge.sh/api/public/calc/force-carbonation?temperature=4&co2=2.5
FAQ
Questions & answers
How much priming sugar do I need for 5 gallons?
For 5 gallons at a typical 2.4 volumes, after fermenting at 68 °F: about 4.4 oz (125 g) of corn sugar or 4.1 oz (117 g) of table sugar. That is roughly 2.3 g of corn sugar per 12 oz bottle. Beer fermented colder needs less, so enter your own temperature.
Which beer temperature do I enter?
The warmest temperature the beer reached at or after the end of fermentation, for example during a diacetyl rest. That is when it lost the most CO₂. The temperature on bottling day is usually lower and would make the calculator assume more CO₂ is still in the beer than really is.
Can I use table sugar instead of corn sugar?
Yes. Table sugar ferments completely and does not affect flavor at priming amounts. You just need about 7% less of it than corn sugar for the same carbonation. Pick the sugar you use in the calculator and it adjusts the amount.
What PSI should I set to force carbonate a keg?
It depends on temperature and target. For 2.4 volumes at 38 °F, about 10 psi; for 2.5 volumes, about 11 psi. Warmer beer needs more pressure. Leave the keg at that pressure for about a week and the beer reaches the target.
How do I avoid bottle bombs?
Bottle only when fermentation is finished and the gravity has stayed the same for a few days. Weigh the sugar instead of using spoons, dissolve it in a little boiled water and stir it evenly into the whole batch. For highly carbonated styles, use bottles made for that pressure.
Can I prime with wort instead of sugar?
Yes, priming with saved wort (in German called Speise) is a traditional method. This calculator works with sugar and dry malt extract, not with wort. How much wort you need depends on its gravity and how far it will ferment.
Do the math once. BrewForge does it every brew.
Recipes, brew day and fermentation in one place, with these calculations built in. Free for up to 20 brews.