Beer Priming Sugar Calculator

Bottle conditioning works by giving yeast a small, final amount of fermentable sugar sealed inside the bottle. As that sugar ferments, the CO2 it produces has nowhere to escape, so it dissolves back into the beer instead. Get the sugar amount right and you land at your target carbonation; too little leaves the beer flat, too much builds dangerous pressure.

Your beer already holds some dissolved CO2 from the main fermentation, and how much depends on temperature: colder beer holds more, warmer beer holds less. This calculator estimates that residual CO2 from the highest temperature your beer reached after fermentation, then works out how much more you need to reach your target.

The three sugar types shown are alternatives, not a combined dose. Corn sugar (dextrose monohydrate) and table sugar (sucrose) are both nearly fully fermentable; corn sugar needs slightly more by weight because of the water bound into its crystal structure. DME is only around 45 percent fermentable sugar by weight, so it takes roughly double the amount of corn sugar to reach the same carbonation.

Over-priming is a genuine safety issue, not just a quality one. Excess CO2 pressure inside a sealed glass bottle can cause it to fail, sometimes violently. Always weigh priming sugar on a scale rather than estimating by volume with a spoon or cup, since sugar density varies enough between batches and brands to throw off a volume-based guess.

Use bottles actually rated for carbonation, such as proper beer bottles or swing-top bottles designed for pressure, never single-use wine or juice bottles. Store conditioning bottles somewhere they can be safely contained if one does fail, and never add extra sugar beyond a calculated dose on the assumption that more carbonation is simply better.