Priming Sugar Calculator
How much sugar to add at bottling so home-brewed beer carbonates to the level you want — allowing for the CO₂ already in it.
Yeast turns bottling sugar into CO₂ in the sealed bottle.
How the priming sugar calculator works
Yeast turns bottling sugar into CO₂ in the sealed bottle. Beer already holds some CO₂ from fermentation, more the colder it finished, so the sugar only needs to make up the difference to the target — about 2.4 volumes for an ale, 2.6 for a lager, 3+ for wheat beers. Table sugar gives about 0.51 g of CO₂ per gram; dextrose (glucose monohydrate) about 0.46, so it takes a little more.
Formula: residual CO₂ = 3.0378 − 0.050062 T(°F) + 0.00026555 T²; sugar = (target − residual) × 1.96 g/L ÷ CO₂ yield per g
Worked examples
| Inputs | Priming sugar | Note |
|---|---|---|
| 20 L ale to 2.4 vol, fermented at 20 °C, table sugar | 118 g | about 116 g |
| 5 US gal lager to 2.6 vol at 12 °C, dextrose | 120 g | about 114 g |
| Wheat beer to 3.2 vol | 180 g | about 177 g |
FAQFrequently asked questions
What carbonation level should I aim for?
British ales 1.5–2.0 volumes, most ales and lagers 2.2–2.7, Belgian and wheat beers 3.0–4.0. Above about 3 volumes, use bottles rated for the pressure.
Why does beer temperature matter?
Beer holds dissolved CO₂ from fermentation, more when it is cold. The calculator subtracts that residual so you do not over-prime; use the warmest temperature the beer reached after fermentation finished.
Table sugar or dextrose?
Either works. Dextrose (corn sugar) is what most kits supply and ferments cleanly; it takes about 10% more by weight because it is a monohydrate with less fermentable mass per gram.
How long until it is carbonated?
Two to three weeks at around 20 °C. Keep the bottles warm for that period and then chill; a test bottle in plastic tells you when it has gone firm.
Where these figures come from
- US FDA — Safe Minimum Internal Temperatures — the internal temperatures the roasting calculator targets
- NIST SP 811 — Guide for the Use of the International System of Units — the exact weight and volume conversions used throughout
- US Food and Drug Administration — food safety and labelling standards
Last checked: September 2026. Baking ratios follow standard baker's percentage practice; roasting guidance follows published safe internal temperatures.