How much priming sugar for 5 gallons?
For a typical ale — 5 gallons to 2.5 volumes of CO₂, the beer having sat no warmer than 68 °F since it finished — it's 137 g of corn sugar, about 4.8 oz. The arithmetic has three parts, and the middle one is where every mistake lives:
sugar = (target − residual) × 1.96 g/L × liters ÷ CO₂ per gram of sugar · (2.5 − 0.86) × 1.96 × 18.9 ÷ 0.444 = 137 g
One "volume" is a liter of CO₂ per liter of beer — 1.96 g of gas. The beer already holds some from fermentation, so the sugar only has to make up the difference, and a gram of sugar makes a fixed amount of gas. That's it. The whole difficulty is knowing what the beer already holds.
Which temperature do you enter? The one everyone gets wrong
Beer out of a fermenter isn't flat. It holds whatever CO₂ stays dissolved at the warmest it's been since the yeast stopped — about 0.86 volumes at 68 °F, 1.5 at 38 °F. While fermentation is running, the yeast replaces whatever escapes, so the peak during fermentation doesn't matter. Once it stops, gas that leaves in a warm spell is gone for good; crashing the beer to 38 °F afterwards makes it able to hold more, but there's nothing left to make more.
Temperature labels vary between calculators. Brewer's Friend's priming guidance discusses the role of fermentation and current temperature. This model uses the warmest sustained temperature after active fermentation as a practical estimate of retained gas in vented beer. Pressure, time, and gas exchange can change the real residual CO₂. Here is how temperature choices affect the same 5-gallon example:
| You enter | Calculator assumes | Corn sugar | Beer actually ends at |
|---|---|---|---|
| 38 °F Cold-crash temperature | 1.52 vol residual | 82 g | 1.84 vol — flat |
| 50 °F Cellar | 1.20 vol residual | 109 g | 2.16 vol — flat |
| 68 °F Warmest after fermentation ended — the right one | 0.86 vol residual | 137 g | 2.50 vol |
| 75 °F Warm spell during active fermentation | 0.78 vol residual | 144 g | 2.58 vol |
| 80 °F Summer garage | 0.73 vol residual | 148 g | 2.63 vol |
5 gal, target 2.5 volumes, corn sugar. "Ends at" assumes the true warmest since fermentation ended was 68 °F. Computed by this page's engine.
The two ways to get it wrong are not symmetric. Enter the cold-crash temperature and you use 40% less sugar than you should — less carbonation than intended. Enter a temperature warmer than the beer really reached after finishing and you over-prime, and that's the direction the glass cares about.
Use the best-supported temperature history after active fermentation, not the cold-crash reading. A warmer input estimates less residual CO₂ and therefore calls for more sugar; guessing warm is not a conservative correction. If the history is uncertain, resolve what you can and consider a lower carbonation target. The calculator cannot establish packaging safety or account for an unresolved fermentation stall.
Priming sugar chart (printable)
Corn sugar by target and batch, warmest temperature 68 °F. The strip underneath gives the residual at other temperatures — use the calculator, or subtract the difference from your target and read the table at that.
| Target (vol) | 5 gal · 19 L | 5.5 gal · 21 L | 6 gal · 23 L | 10 gal · 38 L |
|---|---|---|---|---|
| 1.8 | 79 g · 2.8 oz | 86 g · 3 oz | 94 g · 3.3 oz | 157 g · 5.5 oz |
| 2.0 | 95 g · 3.4 oz | 105 g · 3.7 oz | 114 g · 4 oz | 191 g · 6.7 oz |
| 2.2 | 112 g · 4 oz | 123 g · 4.3 oz | 134 g · 4.7 oz | 224 g · 7.9 oz |
| 2.4 | 129 g · 4.5 oz | 142 g · 5 oz | 154 g · 5.4 oz | 257 g · 9.1 oz |
| 2.5 | 137 g · 4.8 oz | 151 g · 5.3 oz | 165 g · 5.8 oz | 274 g · 9.7 oz |
| 2.6 | 145 g · 5.1 oz | 160 g · 5.6 oz | 175 g · 6.2 oz | 291 g · 10.3 oz |
| 2.8 | 162 g · 5.7 oz | 178 g · 6.3 oz | 195 g · 6.9 oz | 324 g · 11.4 oz |
| 3.0 | 179 g · 6.3 oz | 197 g · 6.9 oz | 215 g · 7.6 oz | 358 g · 12.6 oz |
| Warmest since finishing | 40 °F 4 °C | 45 °F 7 °C | 50 °F 10 °C | 55 °F 13 °C | 60 °F 16 °C | 65 °F 18 °C | 68 °F 20 °C | 70 °F 21 °C | 75 °F 24 °C | 80 °F 27 °C |
|---|---|---|---|---|---|---|---|---|---|---|
| Residual CO₂ (vol) | 1.46 | 1.32 | 1.20 | 1.09 | 0.99 | 0.91 | 0.86 | 0.83 | 0.78 | 0.73 |
Table sugar: use 86% of the corn-sugar weight. DME: ×1.21. Honey: ×1.14. Residual from the standard fit to ASBC solubility data; sugar yields from stoichiometry. Computed by this page's engine.
Corn sugar vs table sugar vs DME vs honey
They all make the same gas by the same reaction — a hexose molecule ferments to two of alcohol and two of CO₂, 0.489 g of gas per gram of sugar. What differs is how much fermentable sugar a gram of the product contains. For the same 5-gallon batch:
| Sugar | CO₂ per gram | For 5 gal to 2.5 vol | Why |
|---|---|---|---|
| Corn sugar (dextrose) | 0.444 g | 137 g · 4.8 oz | Dextrose monohydrate — 9% of its weight is water of crystallization. |
| Table sugar (sucrose) | 0.514 g | 118 g · 4.2 oz | Inverts to two hexoses, taking up water for free — the most CO₂ per gram. |
| Dry malt extract | 0.366 g * | 166 g · 5.9 oz | About 75% fermentable; varies by maltster. Slower, and adds a little body. |
| Honey | 0.391 g * | 156 g · 5.5 oz | About 80% sugars, the rest water; varies by honey. Weigh it, never spoon it. |
* DME and honey are averages — real products vary by maltster and by honey. Corn and table sugar use theoretical stoichiometric yields; real fermentation can differ. Warmest 68 °F.
This calculator models corn sugar as dextrose monohydrate. Its water of crystallization is 9% of the mass, so its theoretical CO₂ yield is 0.444 g/g rather than 0.489 g/g for anhydrous glucose. Check your product. Differences between calculators can also come from residual CO₂ and fermentation-yield assumptions; do not automatically add a percentage to a dose that already accounts for monohydrate.
How many volumes of CO₂ for each style?
| Style | Volumes | Corn sugar, 5 gal, mid-range | Bottle at 70 °F, top of range |
|---|---|---|---|
| British ales, cask-style | 1.5–2 | 74 g · 2.6 oz | 21 psi |
| Porter, stout | 1.7–2.3 | 95 g · 3.4 oz | 26 psi |
| Belgian ales | 1.9–2.4 | 108 g · 3.8 oz | 27 psi |
| American ales | 2.2–2.7 | 133 g · 4.7 oz | 32 psi |
| European lagers | 2.2–2.7 | 133 g · 4.7 oz | 32 psi |
| German wheat beer | 3.3–4.5 | 254 g · 9 oz | 61 psi — rated bottles only |
Ranges as published by Brewer's Friend and the BJCP. Warmest 68 °F. Pressure from the standard Henry's-law fit. Computed by this page's engine.
Bottle bombs: the number that decides whether the glass survives
Carbonation and temperature determine equilibrium pressure. The model puts 2.5 volumes at about 29 psi at 70 °F, and 4.5 volumes at about 61 psi. Bottle strength depends on its design, condition, and manufacturer's rating. The 3-volume marker here is a caution threshold, not a universal rating for ordinary or swing-top bottles.
- The beer must be finished. Two hydrometer readings, several days apart, should agree, and the final gravity must have a plausible explanation. A stable stall is not completed fermentation. Priming a beer that's still fermenting adds your sugar on top of whatever it hasn't eaten yet, and no calculator can see that.
- Weigh, don't measure. "Three-quarters of a cup" varies by a third depending on how it's packed. A $10 kitchen scale removes the biggest error on this page.
- Dissolve and distribute. Boil the sugar in a cup or two of water, cool it, put it in the bottling bucket first and rack the beer onto it gently. Stir once, from the bottom, without splashing. Individual dosing requires an accurate dose in every bottle; avoid guessing by spoonful.
- Use bottles rated for the intended carbonation and storage conditions. Do not infer a rating from the closure or appearance. If a batch may already be overpressurized, avoid unnecessary handling and keep people away; cooling does not remove existing pressure.
The residual-gas formula and fermentation yields are estimates. Measure the packaged volume and sugar carefully, use an appropriate bottle, and resolve unexplained gravity before priming. A precise-looking dose cannot compensate for unfinished fermentation.
Corrected October 10, 2026: A warmer temperature input increases the calculated sugar dose; it is not a conservative guess.