How to use the priming sugar calculator
- Enter the volume of beer going into bottles (after leaving the sediment behind).
- Choose a target carbonation in volumes of CO₂ — see the style table below.
- Enter the highest temperature the beer reached after fermentation finished.
- Pick your priming sugar. Weigh it on a kitchen scale for accuracy.
The formulas
Residual CO₂ (vol) = 3.0378 − 0.050062 × T + 0.00026555 × T² (T in °F) CO₂ to add (g) = (Target − Residual) × Litres × 1.977 g/L Table sugar (g) = CO₂ ÷ 0.514 (sucrose → CO₂ by fermentation) Corn sugar (g) = CO₂ ÷ 0.444 (dextrose monohydrate)
Worked example
5 US gallons (18.9 L) of pale ale, target 2.5 volumes, beer reached 68 °F:
- Residual CO₂ = 0.86 vol
- CO₂ to add = (2.5 − 0.86) × 18.9 × 1.977 ≈ 61 g
- Corn sugar = 61 ÷ 0.444 ≈ 138 g (4.9 oz); table sugar ≈ 119 g (4.2 oz)
Carbonation by beer style
| Style | Volumes of CO₂ |
|---|---|
| British ales, bitters, milds | 1.5–2.0 |
| Porter and stout | 1.7–2.3 |
| American ales and IPAs | 2.2–2.7 |
| Lagers and pilsners | 2.4–2.7 |
| Belgian ales | 2.5–3.2 |
| German wheat beers | 3.0–4.0 |
| Sparkling cider | 2.5–3.0 |
Bottling step by step
- Confirm fermentation is complete: the hydrometer reading is the same for 2–3 days.
- Sanitize bottles, caps, bottling bucket, tubing and filler.
- Dissolve the weighed priming sugar in about 1–2 cups of water, boil for a few minutes and let it cool.
- Pour the sugar solution into the bottling bucket and rack the beer onto it gently to mix without splashing.
- Fill bottles leaving about 1 in (2–3 cm) of headspace, cap, and store at 68–72 °F for two to three weeks.
Safety and troubleshooting
- Flat beer: often too cold during conditioning, or not enough yeast left after long aging — warm the bottles and wait, or add a little fresh yeast at bottling next time.
- Over-carbonated or gushing: too much sugar, bottling early, or infection. Chill the bottles to slow it and open them carefully over a sink.
- High carbonation styles: use heavy Belgian or champagne bottles above about 3 volumes.
- Carbonation drops work well for small batches but give less control than weighed sugar.
Choosing a priming sugar
Corn sugar (dextrose) is the traditional choice because it dissolves easily and ferments completely without adding flavour. Table sugar (sucrose) works just as well and is cheaper; you simply need less of it. Dry malt extract keeps an all-malt beer all-malt, but its fermentability varies by brand, so carbonation is a little less predictable and you need more of it. Honey can add a faint floral note; its water content varies, so treat the result as an estimate. Whatever you use, weigh it rather than measuring by volume — a cup of corn sugar can weigh anywhere from about 130 to 160 grams depending on how tightly it is packed.
The amount per bottle shown by the calculator is useful when you prime bottles individually, for example when bottling a small test batch or splitting a batch into different carbonation levels. For full batches, batch priming in a bucket gives more even results.