Beer Priming Sugar Calculator
Calculate the exact amount of priming sugar for homebrewed beer.
Accounts for residual CO₂, beer temperature, volume, and sugar type.
How Priming Sugar Works
After primary fermentation, beer tastes flat. Most of the CO₂ has bubbled out through the airlock, though never all of it. Adding a small, precise amount of sugar before bottling gives the remaining yeast just enough food to produce carbonation inside the sealed bottle.
Residual CO₂
Beer always contains some dissolved CO₂ from fermentation. The amount depends on the highest temperature the beer reached during fermentation.
Residual CO₂ (volumes) = 3.0378 − (0.050062 × T°F) + (0.00026555 × T°F²)
CO₂ Volumes by Style
| Beer Style | Target CO₂ (volumes) |
|---|---|
| British ales (cask) | 1.5 – 2.0 |
| American ales | 2.2 – 2.7 |
| European lagers | 2.4 – 2.6 |
| Belgian ales | 2.8 – 3.5 |
| Wheat beers (Hefeweizen) | 3.3 – 4.5 |
| Champagne/Méthode | 5.0 – 6.0 |
Sugar Types
- Table sugar (sucrose): fully fermentable, and the reference point for the rest. It takes 0.51 oz per gallon for each volume of CO₂ you need to add, which is 3.8 grams per liter per volume.
- Corn sugar (dextrose): slightly less sweet, dissolves easily. Requires ~11% more by weight than table sugar.
- Dry Malt Extract (DME): adds a slight malt flavor. Requires ~60% more than table sugar.
- Honey: natural choice for meads and specialty beers. Variable fermentability (~75%).
Put through a real batch, that per-gallon rate lands where every homebrewing book does. Five gallons of ale fermented at 70°F holds 0.83 volumes of its own, so hitting 2.4 volumes means adding 1.57, and 0.51 × 1.57 × 5 comes to 4.0 oz (113 g) of table sugar, or 4.5 oz of corn sugar. That is the familiar three quarters of a cup of corn sugar per five gallon batch. If a priming figure ever comes out in the tens of ounces, something is wrong by an order of magnitude, and the bottles will tell you loudly.
Why the weight matters so much
Priming is the one step in homebrewing where a factor-of-two error is genuinely dangerous. The sugar ferments in a sealed bottle, so all the CO₂ stays put. Standard longneck glass is comfortable to roughly 3.5 volumes, Belgian bottles a bit past 4, and beyond that you want champagne bottles with a cage. Double-dose a batch and the bottles do not simply taste fizzy. They fail, sometimes days later, and they throw glass.
Pro Tips
- Dissolve priming sugar in ~1 cup of boiling water, then cool before adding to beer.
- Mix gently after adding — stirring too hard can oxidize the beer.
- Condition bottles at room temperature for 2–3 weeks before chilling.
- Store a “tester” bottle to check carbonation progress.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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